[rtl] Bump the size of plic to 0x08000000

This will make sufficient space to accommodate the MSIP0 registers.

Signed-off-by: Douglas Reis <doreis@lowrisc.org>

Author: engdoreis

data/xbar_main.hjson

@@ -213,7 +213,7 @@
       addr_range: [{
         // This block is overaligned to 0x0800_0000 bytes since OpenTitan RV_PLIC block expects it.
         base_addr: "0x88000000",
-        size_byte: "0x04000000",
+        size_byte: "0x08000000",
       }],
       pipeline: true,
     },