wifi: rtw89: sar: add supported UNII-4 frequency range along with UNII-3 of SAR subband

The UNII-4 uses the same SAR value of UNII-3, so add UNII-4 frequency
range and change the enum name to represent UNII-3 and UNII-4.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20241009071619.16841-1-pkshih@realtek.com