wifi: rtw89: mac: add mac_gen_def::band1_offset to map MAC band1 register address

There are two copies of MAC hardware called band0 and band1. Basically,
the only difference between them is base address, so we can share functions
with a 'band' (or 'mac_idx') argument.

The offset of base address of WiFi 6 and 7 are 0x2000 and 0x4000
respectively, so add band1_offset field to new introduced struct
mac_gen_def to possibly reuse functions.

Using below spatch script to convert callers:

  @@
  expression reg, band;
  @@
  - rtw89_mac_reg_by_idx(reg, band)
  + rtw89_mac_reg_by_idx(rtwdev, reg, band)

  @@
  expression reg, port, band;
  @@
  - rtw89_mac_reg_by_port(reg, port, band)
  + rtw89_mac_reg_by_port(rtwdev, reg, port, band)

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230822125822.23817-2-pkshih@realtek.com