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

Reduces moaning when building on a machine without palo installed.
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>

arch/parisc/Makefile

@@ -77,7 +77,7 @@ libs-y	+= arch/parisc/lib/ `$(CC) -print-libgcc-file-name`
 
 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)