ANDROID: gki_defconfig: remove CONFIG_INIT_STACK_ALL_ZERO=y

Thanks to commit bdcb1d7c ("hardening: Avoid harmless Clang option
under CONFIG_INIT_STACK_ALL_ZERO"), this is now the default, no need to
specify it explicitly.  So remove it from the gki_defconfig files so
that the build works properly again.

Fixes: bdcb1d7c ("hardening: Avoid harmless Clang option under CONFIG_INIT_STACK_ALL_ZERO")
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I32715acc4fcdd98f6ab05fa698571cf3e744db41