leds: Remove asic3 driver

Since ASIC3 MFD driver is removed, the LED support is also
obsolete.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230105134622.254560-25-arnd@kernel.org