b43: add channel info table for N-PHY r8 + radio 2057 r8

b43: add channel info table for N-PHY r8 + radio 2057 r8

Add the 2.4 GHz channel info table for N-PHY rev 8 paired with
radio 2057 rev 8 and wire it to the existing dispatcher in
r2057_get_chantabent_rev7().

The dispatcher's case 8 currently handles radio_rev == 5 only.
For radio_rev == 8 both output pointers stay NULL,
b43_nphy_set_channel() returns an error and channel switch to
the default channel fails.

The new b43_nphy_chantab_phy_rev8_radio_rev8[] is 14 entries
covering the standard 2.4 GHz channel set (2412..2472 in 5 MHz
steps, plus 2484 for channel 14).

Values extracted from an MMIO dump of the proprietary Broadcom wl
driver running on BCM6362 silicon (wl driver 6.30.102.7).

Assisted-by: Claude:claude-4.7-opus
Signed-off-by: Alessio Ferri <alessio.ferri@mythread.it>
Acked-by: Michael Büsch <m@bues.ch>
Reviewed-by: Joshua Peisach <jpeisach@ubuntu.com>
Link: https://patch.msgid.link/20260528-b43_complete_n_phy_rev_8_radio_2057_rev_8_support-v4-6-464566194d47@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>