[PATCH] ppc64: fix prom.c compile warning

The code in unflatten_device_tree knows that get_property is written to
only return with lenp equal to 1 when also returning a valid pointer.
The gcc 3.3.3 compiler is not able to prove this to itself, so it warns
about a possible uninitialized pointer dereference:

 .../arch/ppc64/kernel/prom.c: In function `unflatten_device_tree':
 .../arch/ppc64/kernel/prom.c:828:
 warning: `p' might be used uninitialized in this function

Unless it is desired to rework the interaction between the two
functions, this will keep the existing behavior but quiet the compiler.

Signed-off-by: Amos Waterland <apw@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>