arm64: defconfig: Enable PSTORE_RAM

Enable PSTORE_RAM, that is the ramoops driver, in the defconfig, to
allow logging and retrieving panics and oopses to/from RAM automatically
for platforms that have a ramoops reserved memory node in DT.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: David Heidelberg <david@ixit.cz>
Link: https://lore.kernel.org/r/20240110210600.787703-3-nfraprado@collabora.com
Signed-off-by: Kees Cook <keescook@chromium.org>