Revert "drm/connector: add mutex to protect ELD from concurrent access"

This reverts commit f2196ad7 which is
commit df7c8e3d upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I0091e241671524b1f7e36aa51496b0661b05fe8b
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>