Make CPURead/WriteFunc structure 'const'

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/hw/pflash_cfi02.c b/hw/pflash_cfi02.c
index a62d609..a97b9e6 100644
--- a/hw/pflash_cfi02.c
+++ b/hw/pflash_cfi02.c
@@ -492,13 +492,13 @@
     pflash_write(pfl, addr, value, 4);
 }
 
-static CPUWriteMemoryFunc *pflash_write_ops[] = {
+static CPUWriteMemoryFunc * const pflash_write_ops[] = {
     &pflash_writeb,
     &pflash_writew,
     &pflash_writel,
 };
 
-static CPUReadMemoryFunc *pflash_read_ops[] = {
+static CPUReadMemoryFunc * const pflash_read_ops[] = {
     &pflash_readb,
     &pflash_readw,
     &pflash_readl,