ARM: OMAP2+: Fix memory leak in realtime_counter_init()

The "sys_clk" resource is malloced by clk_get(),
it is not released when the function return.

Fixes: fa6d79d2 ("ARM: OMAP: Add initialisation for the real-time counter.")
Signed-off-by: Chen Hui <judy.chenhui@huawei.com>
Message-Id: <20221108141917.46796-1-judy.chenhui@huawei.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>