mfd: smsc-ece1099: Remove driver

This MFD driver has no user. The keypad driver of this device never made
it into the kernel. Therefore, this driver is useless. Remove it.

Signed-off-by: Michael Walle <michael@walle.cc>
Cc: Sourav Poddar <sourav.poddar@ti.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/driver-api/index.rst

@@ -98,7 +98,6 @@ available subsections can be seen below.
    rfkill
    serial/index
    sm501
-   smsc_ece1099
    switchtec
    sync_file
    vfio-mediated-device