kernel/generic: add a missing symbol to the 5.10 kconfig

Add CONFIG_HAVE_ARM_ARCH_TIMER (disabled). A make kernel_oldconfig on cortexa9
will otherwise prompt for its selection. The 5.4 configuration already contains
the same symbol.

Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>

target/linux/generic/config-5.10

@@ -2121,6 +2121,7 @@ CONFIG_HARDENED_USERCOPY=y
 # CONFIG_HARDENED_USERCOPY_PAGESPAN is not set
 CONFIG_HARDEN_EL2_VECTORS=y
 # CONFIG_HARDLOCKUP_DETECTOR is not set
+# CONFIG_HAVE_ARM_ARCH_TIMER is not set
 # CONFIG_HCALL_STATS is not set
 # CONFIG_HDC100X is not set
 # CONFIG_HDC2010 is not set