MIPS: math-emu: do not use bools for arithmetic

GCC-7 complains about a boolean value being used with an arithmetic
AND:

arch/mips/math-emu/cp1emu.c: In function 'cop1Emulate':
arch/mips/math-emu/cp1emu.c:838:14: warning: '~' on a boolean expression [-Wbool-operation]
  fpr = (x) & ~(cop1_64bit(xcp) == 0);    \
              ^
arch/mips/math-emu/cp1emu.c:1068:3: note: in expansion of macro 'DITOREG'
   DITOREG(dval, MIPSInst_RT(ir));
   ^~~~~~~
arch/mips/math-emu/cp1emu.c:838:14: note: did you mean to use logical not?
  fpr = (x) & ~(cop1_64bit(xcp) == 0);    \

Since cop1_64bit() returns and int, just flip the LSB.
Suggested-by: NMaciej W. Rozycki <macro@imgtec.com>
Signed-off-by: NManuel Lauss <manuel.lauss@gmail.com>
Reviewed-by: NMaciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17058/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/math-emu/cp1emu.c

@@ -830,12 +830,12 @@ do {									\
 } while (0)
 
 #define DIFROMREG(di, x)						\
-	((di) = get_fpr64(&ctx->fpr[(x) & ~(cop1_64bit(xcp) == 0)], 0))
+	((di) = get_fpr64(&ctx->fpr[(x) & ~(cop1_64bit(xcp) ^ 1)], 0))
 
 #define DITOREG(di, x)							\
 do {									\
 	unsigned fpr, i;						\
-	fpr = (x) & ~(cop1_64bit(xcp) == 0);				\
+	fpr = (x) & ~(cop1_64bit(xcp) ^ 1);				\
 	set_fpr64(&ctx->fpr[fpr], 0, di);				\
 	for (i = 1; i < ARRAY_SIZE(ctx->fpr[x].val64); i++)		\
 		set_fpr64(&ctx->fpr[fpr], i, 0);			\