sparc64: fix sparse warnings in compat_audit.c

Fix following warnings:
compat_audit.c:4:10: warning: symbol 'sparc32_dir_class' was not declared. Should it be static?
compat_audit.c:9:10: warning: symbol 'sparc32_chattr_class' was not declared. Should it be static?
compat_audit.c:14:10: warning: symbol 'sparc32_write_class' was not declared. Should it be static?
compat_audit.c:19:10: warning: symbol 'sparc32_read_class' was not declared. Should it be static?
compat_audit.c:24:10: warning: symbol 'sparc32_signal_class' was not declared. Should it be static?
compat_audit.c:29:5: warning: symbol 'sparc32_classify_syscall' was not declared. Should it be static?

Add declarations to kernel.h

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