mips: ralink: match all supported system controller compatible strings

Recently, A new clock and reset controller driver has been introduced to
the ralink mips target[1]. It provides proper system control and adds more
SoC specific compatible strings. In order to better initialize CPUs, this
patch removes the outdated "ralink,mt7620a-sysc" and add all dt-binding
documented compatible strings to the system controller match table.

[1] https://lore.kernel.org/all/20230619040941.1340372-1-sergio.paracuellos@gmail.com/

Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
Reviewed-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>