ARM: mach-omap1: clean up debug-macro.S

This achieves two goals:

1) Get rid of omap_uart_v2p() and omap_uart_p2v() which were the last users
   of PLAT_PHYS_OFFSET.

2) Remove the probing of the M bit in the CP15 control reg and make
   the access to the .data variables completely position independent.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>