[PATCH] powerpc: udbg_printf() formatting attribute

This patch allows the compiler to catch any printf-like mismatches for
udbg_printf().  After some brute force building I've only found issues
with my own code and lparcfg.c It could break some developers, but
IMHO that would be goodness.

Signed-off-by: Jimi Xenidis <jimix@watson.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>