ITE: dts: it82xx2: Increase sram to 256KB

1. Increase sram to 256KB.
   A block sram of SCAR0~15 is 4KB.
   A block sram of SCAR16~19 is 16KB.
   A block sram of SCAR20~23 is 32KB.

2. Removed the register of RVILMCR which has no effect.

Signed-off-by: Tim Lin <tim2.lin@ite.corp-partner.google.com>