mciavi32: Remove unneeded casts.

dlls/mciavi32/mciavi.c

diff --git a/dlls/mciavi32/mciavi.c b/dlls/mciavi32/mciavi.c
index dbd2a3b..84f9077 100644
--- a/dlls/mciavi32/mciavi.c
+++ b/dlls/mciavi32/mciavi.c
@@ -305,7 +305,7 @@
 
     MCIAVI_mciStop(wDevID, MCI_WAIT, NULL);
 
-    wma = (WINE_MCIAVI *)MCIAVI_mciGetOpenDev(wDevID);
+    wma = MCIAVI_mciGetOpenDev(wDevID);
     if (wma == NULL) 	return MCIERR_INVALID_DEVICE_ID;
 
     EnterCriticalSection(&wma->cs);
@@ -402,7 +402,7 @@
 
     if (lpParms == NULL)	return MCIERR_NULL_PARAMETER_BLOCK;
 
-    wma = (WINE_MCIAVI *)MCIAVI_mciGetOpenDev(wDevID);
+    wma = MCIAVI_mciGetOpenDev(wDevID);
     if (wma == NULL)		return MCIERR_INVALID_DEVICE_ID;
 
     EnterCriticalSection(&wma->cs);

dlls/mciavi32/mmoutput.c

diff --git a/dlls/mciavi32/mmoutput.c b/dlls/mciavi32/mmoutput.c
index 1be8266..d1ed699 100644
--- a/dlls/mciavi32/mmoutput.c
+++ b/dlls/mciavi32/mmoutput.c
@@ -494,7 +494,7 @@
 static void CALLBACK MCIAVI_waveCallback(HWAVEOUT hwo, UINT uMsg, DWORD_PTR dwInstance,
                                         DWORD_PTR dwParam1, DWORD_PTR dwParam2)
 {
-    WINE_MCIAVI *wma = (WINE_MCIAVI *)MCIAVI_mciGetOpenDev(dwInstance);
+    WINE_MCIAVI *wma = MCIAVI_mciGetOpenDev(dwInstance);
 
     if (!wma) return;