misc: sram: fix error path in sram_probe

The pool is created thru devm_gen_pool_create, so the call to
gen_pool_destroy is not necessary.
Instead the sram-clock must be turned off again if it exists.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Ulrich Prinz <ulrich.prinz@googlemail.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>