MIPS: MT: Remove SMTC support

Nobody is maintaining SMTC anymore and there also seems to be no userbase.
Which is a pity - the SMTC technology primarily developed by Kevin D.
Kissell <kevink@paralogos.com> is an ingenious demonstration for the MT
ASE's power and elegance.

Based on Markos Chandras <Markos.Chandras@imgtec.com> patch
https://patchwork.linux-mips.org/patch/6719/ which while very similar did
no longer apply cleanly when I tried to merge it plus some additional
post-SMTC cleanup - SMTC was a feature as tricky to remove as it was to
merge once upon a time.

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

arch/mips/include/asm/fixmap.h

@@ -48,11 +48,7 @@
 enum fixed_addresses {
 #define FIX_N_COLOURS 8
 	FIX_CMAP_BEGIN,
-#ifdef CONFIG_MIPS_MT_SMTC
-	FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS * 2),
-#else
 	FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * 2),
-#endif
 #ifdef CONFIG_HIGHMEM
 	/* reserved pte's for temporary kernel mappings */
 	FIX_KMAP_BEGIN = FIX_CMAP_END + 1,