staging: media: davinci_vpfe: remove ret variable in switch statements

Remove ret variable in functions that used it to determine the return.
Simplified the return logic for these functions.

Found with Coccinelle script:

@@
local idexpression ret;
expression c,d;
identifier label;
@@

switch ( ... ) {
case label :
...
- ret = c;
- break;
+ return c;
...
default:
...
- ret = d;
+ return d;
...
}
... when != ret
- return ret;

@@
type T; identifier i;
@@
- T i;
... when != i

Signed-off-by: Thaissa Falbo <thaissa.falbo@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>