dietpi-config: fix flashcp call on Bullseye

In some cases, the function checks whether "-p"/"--partition" is supported, but in other cases it is used unconditionally, probably since Armbian officially dropped Bullseye support anyway.

Author: MichaIng

CHANGELOG.txt

@@ -6,6 +6,7 @@ Enhancements:
 Bug fixes:
 - Raspberry Pi | Resolved an issue on Debian Trixie where the LightDM did not work without enabling KMS/DRM, and hence the related dietpi-autostart option, as well as desktop autologin as non-root user. It is strictly required for recent LightDM and is hence now done automatically. Many thanks to @TheRaven500 for reporting this issue: https://github.com/MichaIng/DietPi/issues/7644#issuecomment-3221254709
 - Rockchip SoCs | Resoved an issue where flashing the SPI bootloader could fail, since "dialog" was called if multiple U-Boot images were available, e.g. to select between M.2 NVMe and SATA support. These calls are now replaced with whiptail, which is pre-installed on DietPi.
+- Rockchip SoCs | Resolved an issue where flashing the SPI bootloader could fail on Bullseye systems, since flashcp was called with the "-p" flag in some cases, supported only from Bookworm on. Many thanks to @Arkem for reporting this issue: https://dietpi.com/forum/t/23426/46
 - DietPi-Config | Resolved a v9.13 regression where setting CPU frequency limits was not possible. This has been solved for DietPi v9.16 as well via live patch. Many thanks to @gitlankford for reporting this issue: https://github.com/MichaIng/DietPi/issues/7696
 - DietPi-Software | Portainer: Resolved a v9.16 regression where the installation could not manage the local Docker environment since the Docker socket was mounted to a wrong path. This has been solved for DietPi v9.16 as well via live patch. Many thanks to @pappv-dd for reporting this issue: https://github.com/MichaIng/DietPi/issues/7691
 

dietpi/dietpi-config

@@ -1133,6 +1133,8 @@ Further information: https://www.raspberrypi.org/documentation/hardware/raspberr
 			# shellcheck disable=SC1091
 			. /usr/lib/u-boot/platform_install.sh
 			eval "$(declare -f write_uboot_platform_mtd | sed -e 's| > /dev/null 2>&1||g' -e 's|status=none|status=progress|g' -e 's/dd /dd oflag=direct conv=notrunc status=progress /' -e 's/exit/return/' -e 's/dialog --no-collapse/whiptail/')"
+			# Bullseye: Remove flashcp "-p" flag
+			(( $G_DISTRO < 7 )) && eval "$(declare -f write_uboot_platform_mtd | sed 's/flashcp -v -p/flashcp -v/')"
 			# shellcheck disable=SC2154
 			write_uboot_platform_mtd "$DIR" "$spidev"