sdhci: Remove Samsung's broken hack

To avoid a divide-by-zero, Samsung returns a 0 if
host->clock is not set.

This is bad - the timeout will (of course) now be
as short as possible.

Mainline does it differently - It uses a base
timeout value regardless of whether host->clock
exists, then adds that value if it exists.

Signed-off-by: Andrew Dodd <atd7@cornell.edu>

thx to Entropy512
 mms_ts: introduce TouchBoost control

thanks to @franciscofranco for the implementation (all credits to him)

i have modded it to be config dependent (CONFIG_TOUCHBOOST_CONTROL), and also
to work with my touchboost mods, which make it working the best way.