hw: Remove unnecessary cast when calling dma_memory_read()

Since its introduction in commit d86a77f8ab, dma_memory_read()
always accepted void pointer argument. Remove the unnecessary
casts.

This commit was produced with the included Coccinelle script
scripts/coccinelle/exec_rw_const.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v4: Drop parenthesis when removing cast (Eric Blake)

scripts/coccinelle/exec_rw_const.cocci

@@ -0,0 +1,23 @@
+/*
+  Usage:
+
+    spatch \
+           --macro-file scripts/cocci-macro-file.h \
+           --sp-file scripts/coccinelle/exec_rw_const.cocci \
+           --keep-comments \
+           --in-place \
+           --dir .
+*/
+
+// Remove useless cast
+@@
+expression E1, E2, E3, E4;
+type T;
+@@
+(
+- dma_memory_read(E1, E2, (T *)(E3), E4)
++ dma_memory_read(E1, E2, E3, E4)
+|
+- dma_memory_write(E1, E2, (T *)(E3), E4)
++ dma_memory_write(E1, E2, E3, E4)
+)