drm/amd/pm/smu7: fix a memleak in smu7_hwmgr_backend_init

The hwmgr->backend, (i.e. data) allocated by kzalloc is not freed in
the error-handling paths of smu7_get_evv_voltages and
smu7_update_edc_leakage_table. However, it did be freed in the
error-handling of phm_initializa_dynamic_state_adjustment_rule_settings,
by smu7_hwmgr_backend_fini. So the lack of free in smu7_get_evv_voltages
and smu7_update_edc_leakage_table is considered a memleak in this patch.

Fixes: 599a7e9f ("drm/amd/powerplay: implement smu7 hwmgr to manager asics with smu ip version 7.")
Fixes: 8f0804c6 ("drm/amd/pm: add edc leakage controller setting")
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>