[MIPS] Transform old-style macros to newer "__noreturn"

Convert old/obsolete NORET_TYPE and ATTRIB_NORET macros to use the
newer standard of "__noreturn" as defined in compiler-gcc.h.

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>