mips: remove SYS_HAS_CPU_MIPS32_R1 from RALINK

All MIPS processors on the Ralink SoCs implement the MIPS32 Release 2
Architecture. Remove SYS_HAS_CPU_MIPS32_R1.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Acked-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>