sh: arch/sh/boot - fix shell usage

Fix the shell call to explicitly use bash, since they are bash
specific and not all systems have bash as the default.

Signed-off-by: David McCullough <david_mccullough@au.securecomputing.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/boot/compressed/Makefile b/arch/sh/boot/compressed/Makefile
index d951241..013504a 100644
--- a/arch/sh/boot/compressed/Makefile
+++ b/arch/sh/boot/compressed/Makefile
@@ -16,9 +16,10 @@
 #
 # IMAGE_OFFSET is the load offset of the compression loader
 #
-IMAGE_OFFSET	:= $(shell printf "0x%08x" $$[$(CONFIG_PAGE_OFFSET)  + \
-					      $(CONFIG_MEMORY_START) + \
-					      $(CONFIG_BOOT_LINK_OFFSET)])
+IMAGE_OFFSET	:= $(shell /bin/bash -c 'printf "0x%08x" \
+		     $$[$(CONFIG_PAGE_OFFSET)  + \
+			$(CONFIG_MEMORY_START) + \
+			$(CONFIG_BOOT_LINK_OFFSET)]')
 
 LIBGCC	:= $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)