generic: 5.15, 6.1: enable CNP support

generic: 5.15, 6.1: enable CNP support

Ever since CONFIG_ARM64_PAN was enabled Common Not Private (CNP) is now
visible and kernel builds will stop as they are not set in kernel config
for 5.15 and 6.1.

So, lets enable Common Not Private (CNP) which is ARMv8.2 feature and will
be NOP of CPU-s that dont support it.

Fixes: a2662309aae1 ("kernel: Enable CONFIG_ARM64_PAN to restrict kernel access to user space memory")
Link: https://github.com/openwrt/openwrt/pull/16211
Signed-off-by: Robert Marko <robimarko@gmail.com>