ARM: mmp: don't select CACHE_TAUROS2 on all ARCH_MMP

MMP3 has a PJ4B with a Tauros 3 cache controller that uses CACHE_L2X0
instead, while CACHE_TAUROS2 is present on PJ4 and PJ1 (Mohawk) based
platforms only.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>