wl12xx_sdio_test: rename files to match current style

Change some file names and Kconfig settings so that this new module matches
the new way of using wl12xx instead of wl1271.

Also fix SDIO power enabling and disabling to match the latest way of doing
it.

Cc: Roger Quadros <roger.quadros@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>