sparc32: fix sparse warning in traps_32.c

Fix following warning:
traps_32.c:47:6: error: symbol 'die_if_kernel' redeclared with different type - different modifiers

Add __noreturn to both definition and declaration

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>