ARM: OMAP2+: gpmc: Print error message in set_gpmc_timing_reg()

Simplify set_gpmc_timing_reg() and always print error message
if the requested timing cannot be achieved due to a too fast
GPMC functional clock, irrespective if whether DEBUG is defined
or not. This should help us debug timing configuration issues,
which were otherwise simply not being displayed in the kernel log.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>