drivers: richtek: fix write-out-of-bounds in rt1711_init_alert()

KASAN warns about a write-out-of-bounds in rt1711_init_alert():

	len = strlen(chip->tcpc_desc->name);
	name = kzalloc(sizeof(len + 5), GFP_KERNEL);        <- allocated here
	sprintf(name, "%s-IRQ", chip->tcpc_desc->name);     <- written here

The stray sizeof() operator means it's allocating 4 bytes rather than
the intended strlen(...) + 5 bytes.

Change-Id: Iaecc36682754948c9fa983ab9a88486690a1358d
Signed-off-by: Greg Hackmann <ghackmann@google.com>