gpio/omap: fix incorrect initialization of omap_gpio_mod_init

Initialization of irqenable, irqstatus registers is the common
operation done in this function for all OMAP platforms, viz. OMAP1,
OMAP2+. The latter _gpio_rmw()'s which supposedly got introduced
wrongly to take care of OMAP2+ platforms were overwriting initially
programmed OMAP1 value breaking functionality on OMAP1.
Somehow incorrect assumption was made that each _gpio_rmw()'s were
mutually exclusive. On close observation it is found that the first
_gpio_rmw() which is supposedly done to take care of OMAP1 platform
is generic enough and takes care of OMAP2+ platform as well.
Therefore remove the latter _gpio_rmw() to irqenable as they are
redundant now.

Writing to ctrl and debounce_en registers for OMAP2+ platforms are
modified to match the original(pre-cleanup) code where the registers
are initialized with 0. In the cleanup series since we are using
_gpio_rmw(reg, 0, 1), instead of __raw_writel(), we are just reading
and writing the same values to ctrl and debounce_en. This is not an
issue for debounce_en register because it has 0x0 as the default value.
But in the case of ctrl register the default value is 0x2 (GATINGRATIO
 = 0x1) so that we end up writing 0x2 instead of intended 0 value.
Therefore changing back to __raw_writel() as this is sufficient for
this case besides simpler to understand.

Also, change irqstatus initalization logic that avoids comparison
with bool, besides making it fit in a single line.

Cc: stable@vger.kernel.org
Cc: Tony Lindgren <tony@atomide.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Reported-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Tested-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>