i.MX25: add AUDMUX and SSI support

* add clocks for audmux and ssi 1 & 2
* add irq for ssi 1 & 2
* add devices platform for ssi1 & 2
* update audmux-v2 for i.MX25
* add base addresses for audmux & ssi 1 & 2
* add iomux configuration for GPIO for AUD5 port

Signed-off-by: Eric Bénard <eric@eukrea.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>