Revert "lpc32xx: cpu: add support for soft reset"

This reverts commit 576007ae.

The parameter passed to reset_cpu() no longer holds a meaning as all
call-sites now pass the value 0.  Thus, branching on it is essentially
dead code and will just confuse future readers.

Revert soft-reset support and just always perform a hard-reset for now.
This is a preparation for removal of the reset_cpu() parameter across
the entire tree in a later patch.

Fixes: 576007ae ("lpc32xx: cpu: add support for soft reset")
Cc: Sylvain Lemieux <slemieux@tycoint.com>
Signed-off-by: Harald Seiler <hws@denx.de>