firmware: make fw->data const

In preparation for supporting firmware files linked into the static
kernel, make fw->data const to ensure that users aren't modifying it (so
that we can pass a pointer to the original in-kernel copy, rather than
having to copy it).

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

include/linux/firmware.h

@@ -8,7 +8,7 @@
 
 struct firmware {
 	size_t size;
-	u8 *data;
+	const u8 *data;
 };
 
 struct device;