The code wants to test if the lower 16bits of the content of
MX53_CSD0_BASE_ADDR and SDRAM_COMPARE_CONST1 are identical. The assembly
this code was derived from did:

	mov             r5, r0, lsl #16
        mov             r6, r7, lsl #16
        cmp             r5, r6

In C this is better written with masks which is better readable and
avoid this compiler warning:

arch/arm/mach-imx/esdctl-v4.c:613:63: warning: result of '305419896 << 16' requires 46 bits to represent, but 'int' only has 32 bits [-Wshift-overflow=]

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>