T480 linux config: add retpoline and USB OHCI HCD requirements for optional USB keyboard support (config menu enabled from ps/2 keyboard required)

[notgivenby]

This PR adds an enhancement against spectre. Moreover, it adds linux configs that are necessary to use HID usb keyboard. If the CONFIG_USB_KEYBOARD_REQUIRED=y without the lines the linux modules are not properly build which results in kernel panic. The issue was discovered during the port of m900_tiny board. notgivenby@adafc97

[tlaurion]

@notgivenby interesting discrepancies and unmeasured perf impact costs on expected fast execution of single user recovery shell tasks (mostly cryptsetup reencryption calls) which are not expected have any other multitasking when under GUI control flow.

I thought retpoline was desired to be off by design (it is something else for kexec'ed final OS considerations).

Either way, linux configs still varies on that matter:

grep -R RETPOLINE config/linux-*
config/linux-c216.config:CONFIG_RETPOLINE=y
config/linux-kgpe-d16_server.config:CONFIG_RETPOLINE=y
config/linux-kgpe-d16_server-whiptail.config:CONFIG_RETPOLINE=y
config/linux-kgpe-d16_workstation.config:CONFIG_RETPOLINE=y
config/linux-librem_common-6.1.8.config:# CONFIG_RETPOLINE is not set
config/linux-librem_common.config:CONFIG_RETPOLINE=y
config/linux-msi-z690-z790.config:# CONFIG_RETPOLINE is not set
config/linux-novacustom-common.config:CONFIG_RETPOLINE=y
config/linux-qemu.config:CONFIG_RETPOLINE=y
config/linux-t440p.config:CONFIG_RETPOLINE=y
config/linux-t480.config:# CONFIG_RETPOLINE is not set
config/linux-w541.config:CONFIG_RETPOLINE=y
config/linux-x230-flash.config:# CONFIG_RETPOLINE is not set
config/linux-x230-flash.config:CONFIG_RETPOLINE=y
config/linux-x230-legacy.config:CONFIG_RETPOLINE=y
config/linux-x230-maximized.config:CONFIG_RETPOLINE=y

TL:DR if goal is unifying configs and enforce same security policies across all boards, msi-z690-z790 and librem_l1um still put RETPOLINE off (x230-flash has it on and off but not supported anymore).

TBH @notgivenby, retpoline being on/off doesn't change much.
LGTM!

[tlaurion]

LGTM merging