mips: mt: include asm/mips_mt.h

mips: mt: include asm/mips_mt.h

These two functions have a global prototype but the header is not included
before the function definitions:

arch/mips/kernel/mips-mt.c:50:6: error: no previous prototype for 'mips_mt_regdump' [-Werror=missing-prototypes]
arch/mips/kernel/mips-mt.c:159:6: error: no previous prototype for 'mips_mt_set_cpuoptions' [-Werror=missing-prototypes]

Link: https://lkml.kernel.org/r/20231204115710.2247097-16-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@rothwell.id.au>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>