iwlwifi: move 3945 SCD registers to iwl-prph.h

This patch moves 3945 SCD registers to iwl-prph.h. These registers
are assigned from the periphery bus

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>