rtc: gamecube: Fix refcount leak in gamecube_rtc_read_offset_from_sram
In the Linux kernel, the following vulnerability has been resolved:

rtc: gamecube: Fix refcount leak in gamecube_rtc_read_offset_from_sram

The of_find_compatible_node() function returns a node pointer with
refcount incremented, We should use of_node_put() on it when done
Add the missing of_node_put() to release the refcount.