This change moves `read_member` and `write_member` helper functions
out of cse_fpt.c and cse_serger.c into cse_helpers.c to avoid
duplication.
BUG=b:189177186,b:189167923
Change-Id: I7b646b29c9058d892bb0fc9824ef1b4340d2510c
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58201
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>