Strip debug symbols from modules (fixup)

allow to also skip the stripping of the modules present in vendor
ramdisk when the BOARD configuration is set to skip the strip step.

there is also a shortcoming of this functionality: it currently assumes
the modules to strip are all created equal against the same arch in
particular, however this does not work for kernel modules which are
for mixed mode platforms, as example {kernel,android} == {aarch64,armv7}
because it will select the "android" mode strip which is unaware of the
kernel mode architecture.

Bug: 156395749
Bug: 155193290
Change-Id: I35ef51845224e94e3e253acdeb6bb14b990a401b