arch: unicore32: ksyms: export additional find_first_*() to avoid compiling failure

Some modules need find_first_bit() and find_first_zero_bit(), so export
them.

The related error (with allmodconfig under unicore32):

    MODPOST 4039 modules
  ERROR: "find_first_bit" [sound/soc/codecs/snd-soc-uda1380.ko] undefined!
  ERROR: "find_first_zero_bit" [net/sctp/sctp.ko] undefined!
  ...
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Acked-by: NXuetao Guan <gxt@mprc.pku.edu.cn>
Signed-off-by: NXuetao Guan <gxt@mprc.pku.edu.cn>

arch/unicore32/kernel/ksyms.c

@@ -23,6 +23,8 @@
 
 #include "ksyms.h"
 
+EXPORT_SYMBOL(find_first_bit);
+EXPORT_SYMBOL(find_first_zero_bit);
 EXPORT_SYMBOL(find_next_zero_bit);
 EXPORT_SYMBOL(find_next_bit);