reset: Add DesignWare IP support to simple reset

The reset-simple driver can be now used on DesignWare IPs by
default by selecting the following compatible strings:
 - snps,dw-high-reset for active high resets inputs
 - snps,dw-low-reset for active low resets inputs

Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Signed-off-by: Luis Oliveira <luis.oliveira@synopsys.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>