unicore32: fix build error for find bitops

unicore32: fix build error for find bitops

Remove the __uc32_ prefix in find bitops functions.
Move find_* macros behind asm-generic/bitops.h inclusion.
see commit <3ae07d08ccf71ce372f0c95772b7fa121420c95b>
  bitops: add #ifndef for each of find bitops
also see commit <eaae2751ba5fa4b2e053e0d9a4519a2a583607d9>
  arch: remove CONFIG_GENERIC_FIND_{NEXT_BIT,BIT_LE,LAST_BIT}

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>