Fixes:
arch/mips/lib/lshrdi3.c:6: warning: no previous prototype for '__lshrdi3'
arch/mips/lib/ashrdi3.c:6: warning: no previous prototype for '__ashrdi3'
arch/mips/lib/ashldi3.c:6: warning: no previous prototype for '__ashldi3'
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>