usb: hcd.h: Remove RUN_CONTEXT

The last user of RUN_CONTEXT was removed in commit
   97c17beb3b668 ("[PATCH] ehci-hcd (1/2):  portability (2.4), tasklet,")
in the history.git repo.

There are no users of RUN_CONTEXT, remove it.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20201113212704.2243807-1-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>