parisc: quiet palo not-found message from "which"

Reduces moaning when building on a machine without palo installed.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
diff --git a/arch/parisc/Makefile b/arch/parisc/Makefile
index 5ddad7b..0d42827 100644
--- a/arch/parisc/Makefile
+++ b/arch/parisc/Makefile
@@ -77,7 +77,7 @@
 
 drivers-$(CONFIG_OPROFILE)		+= arch/parisc/oprofile/
 
-PALO := $(shell if which palo; then : ; \
+PALO := $(shell if (which palo 2>&1); then : ; \
 	elif [ -x /sbin/palo ]; then echo /sbin/palo; \
 	fi)