sdm: Conditionally revert "sdm: Implement ‘Null Display’ in SDM core"

This commit conditionally reverts the add of the member function
`IsDisplayHWAvailable()` from commit
24255680b2c02c809040594c8e7536837118754d.

Change-Id: I9ea381906e98134069993e91429594c59d17efc3
3 files changed