m32r: define CPU_BIG_ENDIAN

m32r: define CPU_BIG_ENDIAN

The build of m32r allmodconfig is giving lots of build warnings about:

  include/linux/byteorder/big_endian.h:7:2:
	warning: #warning inconsistent configuration,
		needs CONFIG_CPU_BIG_ENDIAN [-Wcpp]
	#warning inconsistent configuration, needs CONFIG_CPU_BIG_ENDIAN

Define CPU_BIG_ENDIAN like the way CPU_LITTLE_ENDIAN is defined.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Sudip Mukherjee <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>