Input: elan_i2c - add ic type 0x15

The update firmware flow of ic type 0x15 is same with ic type 0x14.

Signed-off-by: Jingle Wu <jingle.wu@emc.com.tw>
Link: https://lore.kernel.org/r/20200730060526.12439-1-jingle.wu@emc.com.tw


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>