wifi: rtl8xxxu: fix txdw7 assignment of TX DESC v3

wifi: rtl8xxxu: fix txdw7 assignment of TX DESC v3

Type of txdw7 is __le16, so assign __le32 is wrong. Also, the
TXDESC_ANTENNA_SELECT_C is defined for __le32, so shift 16 bits to fit
the value. Compile test only.

sparse warnings: (new ones prefixed by >>)
>> rtl8xxxu_core.c:5198:24: sparse: sparse: invalid assignment: |=
>> rtl8xxxu_core.c:5198:24: sparse:    left side has type restricted __le16
>> rtl8xxxu_core.c:5198:24: sparse:    right side has type restricted __le32

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Tested-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230119113146.9640-1-pkshih@realtek.com