rtlwifi: rtl8188ee: Fix incorrect returned values

In commit 36eda756 ("rtlwifi: rtl8188ee: Convert macros that set
descriptor"), all the routines that get fields from a descriptor were
changed to return signed integer values. This is incorrect for the
routines that get the entire 32-bit word. In this case, an unsigned
quantity is required.

Fixes: 36eda756 ("rtlwifi: rtl8188ee: Convert macros that set descriptor")
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>