A check for CONFIG_CBUS_TAHVO_USB was added in v2.6.17. The related
Kconfig symbol has never been part of the tree. Remove that check.

Replace the while (...) loop with a simple if (...) statement, while
we're at it.
Signed-off-by: NPaul Bolle <pebolle@tiscali.nl>
Acked-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: NTony Lindgren <tony@atomide.com>