ANDROID: fips140: eliminate crypto-fips.a build step

To trick the build system into compiling some source files as built-in
code despite their actual destination being fips140.ko, a layer of
indirection was being used where the files were first built into a
static library crypto-fips.a, and then that static library was linked
into fips140.o before the final link of fips140.ko.

The problem with that approach is that it is incompatible with the usual
behavior of linking, where linking to a static library incorporates only
the needed parts of the library, not the whole library.  The only reason
that it happened to work anyway is due to the dependency of the fips140
module on LTO, combined with a peculiarity of the way that the kernel
build system built LTO modules: the build system actually created
${modname}.o as a static library (despite the .o suffix), and used the
--whole-archive linker flag when linking ${modname}.ko.

commit c25e1c55 ("kbuild: do not create *.prelink.o for Clang LTO or
IBT") in Linux v5.19 changed that.  Now, ${modname}.o is an object file,
and the --whole-archive flag isn't used when linking ${modname}.ko.
Therefore, the crypto-fips.a hack no longer works, as things from this
static library (such as the initcalls) get lost during linking.

Replace it with a different hack that eliminates the dependency on LTO
and should be less fragile: undefine MODULE in fips140-defs.h, and
re-define it in the one file where it is needed.  (For consistency, also
move the definition of __DISABLE_EXPORTS into fips140-defs.h.)

Bug: 188620248
Change-Id: I4a6a5f68381a7540bf37ba610216442dae0d2a7a
Signed-off-by: Eric Biggers <ebiggers@google.com>