Address the following  checkpatch warning by using __func__ instead:
WARNING: Prefer using '"%s...", __func__' to using 'write_ec_cmd',
this function's name, in a string
Signed-off-by: NJiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>