[ARM] 4530/1: MXC: fix elf_hwcap compile breakage as in iop13xx

MXC needs the same change as IOP. See [ARM] 4494/1
or commit 7dea1b20066cd30fb54da7e686b16b5e38b46b2d

An undefined reference to elf_hwcap prevents linkage, due
to changes made by f884b1cf578e079f01682514ae1ae64c74586602
and d1cbbd6b413510c6512f4f80ffd48db1a8dd554a

Removing processor.h removes the extern definition of
elf_hwcap, which fixes the link issue, but forgets cpu_relax().
So, instead, we'll call barrier() directly.

Cc: Lennert Buytenhek <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Acked-by: Ross Wille <[e-mail]>
Signed-off-by: Quinn Jensen <[e-mail]>
Signed-off-by: Russell King <[e-mail]>

include/asm-arm/arch-mxc/uncompress.h

···
 #define __MXC_BOOT_UNCOMPRESS
 
 #include <asm/hardware.h>
-#include <asm/processor.h>
 
 #define UART(x) (*(volatile unsigned long *)(serial_port + (x)))
 
···
 	}
 
 	while (!(UART(USR2) & USR2_TXFE))
-		cpu_relax();
+		barrier();
 
 	UART(TXR) = ch;
 }