BACKPORT: ARM: 9035/1: uncompress: Add be32tocpu macro

DTB stores all values as 32-bit big-endian integers.
Add a macro to convert such values to native CPU endianness, to reduce
duplication.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

(cherry picked from commit 0557ac83fd1a0a7cd6909665bad50006507115a0)
(resolved conflict due to different patch context, caused by missing
 "ARM: 9010/1: uncompress: Print the location of appended DTB")
Bug: 178411248
Change-Id: I0807f36352dbfd5f5808959e358a7469dc9753bb
Signed-off-by: Eric Biggers <ebiggers@google.com>