SPM: Remove 'init' and 'runtime' folder in 'spm/common'

The 'init' was proposed for 'booting' and the 'runtime' was for SPM
runtime usage. These folders are historic items which not following
the structure document, remove them.

Change-Id: I2e9876b992f98325c9f376f899a7ed288ed04b95
Signed-off-by: Summer Qin <summer.qin@arm.com>
6 files changed