Staging: media: Replace dev_err with pr_err to avoid null pointer derefrence

This patch replace dev_err with pr_err, for pointer is derefrenced after comparing it to NULL.
This was found using the following coccinelle script:

@disable is_null@
identifier f;
expression E;
identifier fld;
statement S;
@@

+ if(E == NULL) S
	f(...,E->fld,...);
-if(E == NULL) S;

@@
identifier f;
expression E;
identifier fld;
statement S;
@@

+ if(!E) S
	f(...,E->fld,...);
-if(!E) S;

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>