Changing Addresses of custom registers ICACHE and DCACHE.

Created by: frikhaAziz

ICACHE and DCACHE have an address in 0x700-0x77F which is a Standard read/write in M-mode. But ICACHE and DCACHE are Custom registers so they need to be Custom read/write. In fact there is two possibilities 0x7C0-0x7FF and 0xBC0-0xBFF. I chose the first one 0x7C0-0x7FF. ICACHE: 0x700==>0x7C0. DCACHE: 0X701==>0x7C1.
RTL and Spec are changed to solve #1202 (closed) issue.