ARM: 6700/1: SPEAr: Correct SOC config base address for spear320

SPEAR320_SOC_CONFIG_BASE was wrong, causing the wrong registers to be
accessed.

Reviewed-by: Stanley Miao <stanley.miao@windriver.com>
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>