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>