rtw88: fix memory overrun and memory leak during hw_scan

Previously we allocated less memory than actual required, overwrite
to the buffer causes the mm module to complaint and raise access
violation faults. Along with potential memory leaks when returned
early. Fix these by passing the correct size and proper deinit flow.

Fixes: 10d162b2

 ("rtw88: 8822c: add ieee80211_ops::hw_scan")
Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220121070813.9656-4-pkshih@realtek.com