wifi: rtw88: Use devm_kmemdup() in rtw_set_supported_band()

wifi: rtw88: Use devm_kmemdup() in rtw_set_supported_band()

Simplify the code by using device managed memory allocations.

This also fixes a memory leak in rtw_register_hw(). The supported bands
were not freed in the error path.

Copied from commit 145df52a8671 ("wifi: rtw89: Convert
rtw89_core_set_supported_band to use devm_*").

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/1aa7fdef-2d5b-4a31-a4e9-fac8257ed30d@gmail.com