ARM: OMAP: Don't store timers physical address

The OMAP2+ system timer code stores the physical address of the timer
but never uses it. Remove this and clean-up the code by removing the
local variable "size" and changing the names of the local variables
mem_rsrc and irq_rsrc to mem and irq, respectively.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>