[ibex] Enable PMPs

Enable the maximum of 16 PMPs with the most fine-grained granularity of
a word.

Note that PMP is EXPERIMENTAL at this point and not yet verified on the Ibex
side. Still, enabling it now has two benefits:

- It gives software an early access to test this fundamental functionality
  during operating system development (with the clear expectation that
  the hardware could be buggy).
- Given the significant area increase of Ibex with PMP enabled, it gives
  us a better indication of area and timing pressure across the chip.

Fixes #1445

Signed-off-by: Philipp Wagner <phw@lowrisc.org>

hw/top_earlgrey/data/top_earlgrey.sv.tpl

diff --git a/hw/top_earlgrey/data/top_earlgrey.sv.tpl b/hw/top_earlgrey/data/top_earlgrey.sv.tpl
index 8fd17a8..21dba85 100644
--- a/hw/top_earlgrey/data/top_earlgrey.sv.tpl
+++ b/hw/top_earlgrey/data/top_earlgrey.sv.tpl
@@ -234,9 +234,9 @@
 
   // processor core
   rv_core_ibex #(
-    .PMPEnable                (0),
-    .PMPGranularity           (0),
-    .PMPNumRegions            (4),
+    .PMPEnable                (1),
+    .PMPGranularity           (0), // 2^(PMPGranularity+2) == 4 byte granularity
+    .PMPNumRegions            (16),
     .MHPMCounterNum           (8),
     .MHPMCounterWidth         (40),
     .RV32E                    (0),