brcm2708: fix build failure

brcm2708: fix build failure

Build of the brcm2708 subtarget currently fails with the following error
message:

 arch/arm/lib/memset_rpi.S: Assembler messages:
 arch/arm/lib/memset_rpi.S:65: Error: garbage following instruction
  -- `orr DAT0,DAT0,lsl#8'
 arch/arm/lib/memset_rpi.S:67: Error: garbage following instruction
  -- `orr DAT0,DAT0,lsl#16'
 scripts/Makefile.build:427: recipe for target 'arch/arm/lib/memset_rpi.o'
 failed

Using the assembly notation from master fixes this error.

Signed-off-by: David Bauer <mail@david-bauer.net>