rpmsg: char: Remove useless include

No facility requests the include of rpmsg_internal.h header file.
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210712123752.10449-2-arnaud.pouliquen@foss.st.com

drivers/rpmsg/rpmsg_char.c

@@ -22,8 +22,6 @@
 #include <linux/uaccess.h>
 #include <uapi/linux/rpmsg.h>
 
-#include "rpmsg_internal.h"
-
 #define RPMSG_DEV_MAX	(MINORMASK + 1)
 
 static dev_t rpmsg_major;