m68k: bitops: Change __fls to return and accept unsigned long

As per asm-generic definition and other architectures __fls should
return and accept unsigned long as its parameter.

No functional change is expected as return value should fit in unsigned
long.
Reviewed-by: NCezary Rojewski <cezary.rojewski@intel.com>
Signed-off-by: NAmadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Link: https://lore.kernel.org/r/20220527115345.2588775-3-amadeuszx.slawinski@linux.intel.comSigned-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/include/asm/bitops.h

@@ -510,7 +510,7 @@ static inline int fls(unsigned int x)
 	return 32 - cnt;
 }
 
-static inline int __fls(int x)
+static inline unsigned long __fls(unsigned long x)
 {
 	return fls(x) - 1;
 }