hw/microblaze: Restrict MemoryRegionOps are implemented as 32-bit

All these MemoryRegionOps read() and write() handlers are
implemented expecting 32-bit accesses. Clarify that setting
.impl.min/max_access_size fields.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20241105130431.22564-8-philmd@linaro.org>

hw/intc/xilinx_intc.c

@@ -144,6 +144,10 @@ static const MemoryRegionOps pic_ops = {
     .read = pic_read,
     .write = pic_write,
     .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
     .valid = {
         .min_access_size = 4,
         .max_access_size = 4

hw/net/xilinx_ethlite.c

@@ -166,6 +166,10 @@ static const MemoryRegionOps eth_ops = {
     .read = eth_read,
     .write = eth_write,
     .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
     .valid = {
         .min_access_size = 4,
         .max_access_size = 4

hw/timer/xilinx_timer.c

@@ -193,6 +193,10 @@ static const MemoryRegionOps timer_ops = {
     .read = timer_read,
     .write = timer_write,
     .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
     .valid = {
         .min_access_size = 4,
         .max_access_size = 4