UPSTREAM: mips: Add clock_getres entry point

The generic vDSO library provides an implementation of clock_getres()
that can be leveraged by each architecture.

Add clock_getres() entry point on mips.

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
(cherry picked from commit abed3d826f2fb723c61b1251720348a42357c4e5)
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 154668398
Change-Id: I6f408b668f4e11d706ca243ba997b105ba28a345