[SPARC64]: Fix sparse errors in arch/sparc64/kernel/traps.c

Add 'UL' markers to DCU_* macros.

Declare C functions called from assembler in entry.h

Declare C functions called from within the sparc64 arch
code in include/asm-sparc64/*.h headers as appropriate.

Remove unused routines in traps.c

Signed-off-by: David S. Miller <davem@davemloft.net>