Make CPURead/WriteFunc structure 'const'

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/hw/sh7750.c b/hw/sh7750.c
index ac1cc01..cf9cf16 100644
--- a/hw/sh7750.c
+++ b/hw/sh7750.c
@@ -434,13 +434,13 @@
     }
 }
 
-static CPUReadMemoryFunc *sh7750_mem_read[] = {
+static CPUReadMemoryFunc * const sh7750_mem_read[] = {
     sh7750_mem_readb,
     sh7750_mem_readw,
     sh7750_mem_readl
 };
 
-static CPUWriteMemoryFunc *sh7750_mem_write[] = {
+static CPUWriteMemoryFunc * const sh7750_mem_write[] = {
     sh7750_mem_writeb,
     sh7750_mem_writew,
     sh7750_mem_writel
@@ -688,13 +688,13 @@
     }
 }
 
-static CPUReadMemoryFunc *sh7750_mmct_read[] = {
+static CPUReadMemoryFunc * const sh7750_mmct_read[] = {
     invalid_read,
     invalid_read,
     sh7750_mmct_readl
 };
 
-static CPUWriteMemoryFunc *sh7750_mmct_write[] = {
+static CPUWriteMemoryFunc * const sh7750_mmct_write[] = {
     invalid_write,
     invalid_write,
     sh7750_mmct_writel