drivers/net/can/flexcan.c: add missing clk_put

The failed_get label is used after the call to clk_get has succeeded, so it
should be moved up above the call to clk_put.

The failed_req labels doesn't do anything different than failed_get, so
delete it.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/

)

// <smpl>
@r exists@
expression e1,e2;
statement S;
@@

e1 = clk_get@p1(...);
... when != e1 = e2
    when != clk_put(e1)
    when any
if (...) { ... when != clk_put(e1)
               when != if (...) { ... clk_put(e1) ... }
* return@p3 ...;
 } else S
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>