MIPS: Remove further use of .subsection

7837314d [MIPS: Get rid of branches to
.subsections] removed most uses of .subsection] removed most uses of
.subsection in inline assembler code.

It left the instances in spinlock.h alone because we knew their use was
in fairly small files where .subsection use was fine but of course this
was a fragile assumption.  LTO breaks this assumption resulting in build
errors due to exceeded branch range, so remove further instances of
.subsection.

The two functions that still use .macro don't currently cause issues
however this use is still fragile.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>