SPEAr: Correct SoC ID offset in misc configuration space

SoC Core ID offset is 0x30 in miscellaneous configuration address
space. It was wrongly mentioned as periph2 clk enable.

Signed-off-by: Shiraz Hashim <shiraz.hashim@st.com>
Signed-off-by: Amit Virdi <amit.virdi@st.com>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>