wl12xx: move to new firmware (6.1.3.50.49)

This patch adds support for the new wl12xx firmware (Rev 6.1.3.50.49)

Since this fw is not backward compatible with previous fw versions,
a new fw (with different name) is being fetched.

(the patch is big because it contains all the required fw api changes.
splitting it into multiple patches will result in corrupted intermediate
commits)

Signed-off-by: Eliad Peller <eliad@wizery.com>
Reviewed-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>