[ARM] 4227/1: minor head.S fixups

Let's surround constructs like:

	orr	r3, r3, #(KERNEL_RAM_PADDR & 0x00f00000)

between .if .endif since (KERNEL_RAM_PADDR & 0x00f00000) is 0 in 99% of
all cases.

Also let's mask PHYS_OFFSET with 0x00f00000 instead of 0x00e00000.
Section mappings are really 1MB not 2MB and the 2MB groupping is
a higher level issue already much better enforced with

#if (PHYS_OFFSET & 0x001fffff)
#error "PHYS_OFFSET must be at an even 2MiB boundary!"
#endif

at the top of the file.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>