[SPARC32]: Fix prom.c build warning

Fix these 2.6.19-rc1 build warnings:

  CC      arch/sparc/kernel/prom.o
arch/sparc/kernel/prom.c: In function `of_set_property':
arch/sparc/kernel/prom.c:246: warning: passing arg 2 of `prom_setprop' discards qualifiers from pointer target type
arch/sparc/kernel/prom.c: In function `build_one_prop':
arch/sparc/kernel/prom.c:446: warning: unused variable `len'
arch/sparc/kernel/prom.c:480: warning: ignoring return value of `prom_getproperty', declared with attribute warn_unused_result

Signed-off-by: Martin Habets <errandir_news@mph.eclipse.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/prom.c

@@ -243,7 +243,7 @@ int of_set_property(struct device_node *dp, const char *name, void *val, int len
 			void *old_val = prop->value;
 			int ret;
 
-			ret = prom_setprop(dp->node, name, val, len);
+			ret = prom_setprop(dp->node, (char *) name, val, len);
 			err = -EINVAL;
 			if (ret >= 0) {
 				prop->value = new_val;
@@ -477,7 +477,10 @@ static struct property * __init build_one_prop(phandle node, char *prev, char *s
 			p->length = 0;
 		} else {
 			p->value = prom_early_alloc(p->length + 1);
-			prom_getproperty(node, p->name, p->value, p->length);
+			len = prom_getproperty(node, p->name, p->value,
+					       p->length);
+			if (len <= 0)
+				p->length = 0;
 			((unsigned char *)p->value)[p->length] = '\0';
 		}
 	}