Code bugs're fixed.

Code bugs're fixed.

src/display/core.c 1778:  Declaring variable "i" without initializer.
src/display/core.c  771:  string_null_argument: Function "read(int, void *, size_t)" does not terminate string "*pname"
src/display/core.c  287:  missing_return: Arriving at the end of a function without returning a value.
src/display/poll.c  235:  leaked_storage: Variable "new_dev" going out of scope leaks the storage it points to.

Change-Id: I3eb4d79cdbc1c367bc776a934e3d217ccd70f37d
Signed-off-by: Krzysztof Sasiak <k.sasiak@samsung.com>