ARM: 8317/1: move the .idmap.text section closer to .head.text

This moves the .idmap.text section closer to .head.text, so that
relative branches are less likely to go out of range if the kernel
text gets bigger.

Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>