[][kernel][common][app][Fix coverity issue for the switch utility]

[Description]
Fix coverity issue for the switch utility.

Without this patch, the coverity might detect UNUSED_VALUE warning in
the mii_mgr_cl45_read_indirect() and mii_mgr_cl45_write_indirect().

[Release-log]
N/A


Change-Id: If3428b07a02170e2cfd1529d585b61ca9a50803b
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7947206
1 file changed