omap3: Fix handling some GPIO's for WLAN-BT combo on IGEP v2

Some GPIO's used by WLAN-BT combo on IGEP v2 depends on hardware
revision. This patch handles these GPIO's.

  ----------------------------------------------------------
 |       Hw Rev.       | WIFI_NPD | WIFI_NRESET | BT_NRESET |
  ----------------------------------------------------------
 |  B                  | gpio94  |   gpio95    |     -      |
 |  B/C (B-compatible) | gpio94  |   gpio95    |  gpio137   |
 |  C                  | gpio138 |   gpio139   |  gpio137   |
  ----------------------------------------------------------

Signed-off-by: Enric Balletbo i Serra <eballetbo@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>