platform: generic: andes: Add support for RV32 to set up PMA

Like PMP, the behaviors to configure PMA will be different from
RV64 and RV32. RV64 uses two Andes custom CSRs, pmacfg0 and pmacfg2,
but RV32 uses four Andes custom CSRs, pmacfg0 ~ pmacfg3. This patch
adds support to PMA for RV32.

Signed-off-by: Ben Zong-You Xie <ben717@andestech.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
diff --git a/platform/generic/andes/andes_pma.c b/platform/generic/andes/andes_pma.c
index 321074a..9c37720 100644
--- a/platform/generic/andes/andes_pma.c
+++ b/platform/generic/andes/andes_pma.c
@@ -109,10 +109,17 @@
 	    !(pma_region->flags & ANDES_PMACFG_ETYP_NAPOT))
 		return SBI_EINVAL;
 
+#if __riscv_xlen == 64
 	pma_cfg_addr = CSR_PMACFG0 + ((entry_id / 8) ? 2 : 0);
 	pmacfg_val = andes_pma_read_num(pma_cfg_addr);
 	pmaxcfg = (char *)&pmacfg_val + (entry_id % 8);
-	*pmaxcfg = 0;
+#elif __riscv_xlen == 32
+	pma_cfg_addr = CSR_PMACFG0 + (entry_id / 4);
+	pmacfg_val = andes_pma_read_num(pma_cfg_addr);
+	pmaxcfg = (char *)&pmacfg_val + (entry_id % 4);
+#else
+#error "Unexpected __riscv_xlen"
+#endif
 	*pmaxcfg = pma_region->flags;
 
 	andes_pma_write_num(pma_cfg_addr, pmacfg_val);