mtd: rawnand: tango: Fix struct clk memory leak

Use devm_clk_get() to let Linux manage struct clk memory.

Fixes: 6956e238 ("add tango NAND flash controller support")
Cc: stable@vger.kernel.org
Reported-by: Xidong Wang <wangxidong_97@163.com>
Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>