display: state-transition: Remove default_check()

display: state-transition: Remove default_check()

default_check() was used for checking state transition condition.
If there is any pmlock of the state checked which is not background status,
it is impossible to move next state.
default_check() follows same policy from all plugins.
To move from current display state to next display state, this function is necessary.

Thus, this function is added below display-state-transition.
int display_state_transition_check_state_transition_condition(enum state_t cur_state, enum state_t next_state);

Change-Id: I06adb467ac81a04596f22a7b0fe9b06c3b72d248
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>