[rtl] Explicitly set RV32B/RV32M for Ibex

This is effectively a no-op change. Before the latest Ibex was vendored
we had no bitmanip (the RV32BFull parameter was not fully passed
through) and RV32M was the fast multiplier.

Sadly the single cycle multiplier seems to be increasing timing
pressure. It does just meet timing but greatly increases synthesis
times. As it's implemented with in-built FPGA DSP blocks it shouldn't be
a big issue to use it so something to examine here but for now leave
things as they are.

rtl/system/sonata_system.sv

@@ -770,7 +770,8 @@ module sonata_system
     .HeapBase        ( tl_main_pkg::ADDR_SPACE_SRAM            ),
     .TSMapBase       ( tl_main_pkg::ADDR_SPACE_REV_TAG         ),
     .TSMapSize       ( RevTagDepth                             ),
-    .RV32B           ( ibex_pkg::RV32BFull                     ),
+    .RV32M           ( ibex_pkg::RV32MFast                     ),
+    .RV32B           ( ibex_pkg::RV32BNone                     ),
     .ICache          ( 1'b1                                    )
   ) u_top_tracing (
     .clk_i                  (clk_sys_i),