ANDROID: GKI: enable CONFIG_EROFS_FS=y

Some vendors are using erofs, so instead of having to support this as a
module, build it into the kernel for everyone to use.

Bug: 157965270
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I8f8e953c13991dea50031fb4ff01ee99fbf09b88