ANDROID: GKI: Do not force select MODULE_SIG_ALL

CONFIG_MODULE_SIG_ALL needs to be set for gki_defconig,
but will require an override via device fragments
to avoid signing the vendor modules at build-time.

It defaults to 'y' so no need to explicitly set for
gki_defconfig.

Bug: 200082547
Bug: 214445388
Fixes: 9ab6a242 ("ANDROID: GKI: Add module load time protected symbol lookup")
Test: TH, manual builds including P21 mainline
Signed-off-by: Ramji Jiyani <ramjiyani@google.com>
Change-Id: Iafc0936b5e7bfb781b28642d1ec233a7fcf85f09