MIPS: O32: Use compat_sys_getsockopt.

We were using the native syscall and that results in subtle breakage.

This is the same issue as fixed in 077d0e65
(MIPS: N32: Use compat getsockopt syscall) but that commit did fix it only
for N32.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=100291