staging: wfx: fix highest Rx value declared in ieee80211_supported_band

The highest Rx value declared in ieee80211_supported_band had two
problems:
    1. The value should be little endian
    2. ShortGI was not taken into account. So value should be 72 instead
       of 65.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200427134031.323403-9-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>