MIPS: delay.c: Check BITS_PER_LONG instead of __SIZEOF_LONG__

When building a 32-bit kernel for RBTX4927 with gcc version 4.1.2 20061115
(prerelease) (Ubuntu 4.1.1-21), I get:

arch/mips/lib/delay.c:24:5: warning: "__SIZEOF_LONG__" is not defined

As a consequence, __delay() always uses the 64-bit "dsubu" instruction.

Replace the check for "__SIZEOF_LONG__ == 4" by "BITS_PER_LONG == 32" to
fix this.

Introduced by commit 5210edcd52 [MIPS: Make
__{,n,u}delay declarations match definitions and generic delay.h"]

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Patchwork: https://patchwork.linux-mips.org/patch/4678/
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/lib/delay.c

@@ -21,7 +21,7 @@ void __delay(unsigned long loops)
 	"	.set	noreorder				\n"
 	"	.align	3					\n"
 	"1:	bnez	%0, 1b					\n"
-#if __SIZEOF_LONG__ == 4
+#if BITS_PER_LONG == 32
 	"	subu	%0, 1					\n"
 #else
 	"	dsubu	%0, 1					\n"