wl12xx: fix sdio_test module functionality

Due to some changes in PM in recent kernels, the sdio_test module has
been broken for a while.  This patch fixes the code that powers the
card on and off.

Also made some small indentation fixes in the Makefile.

[Rephrased commit log and removed the change in the FW name, since
it's done in another patch. -- Luca]

Signed-off-by: Shahar Levi <shahar_levi@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>