CSFB SS: Do not show result in case of CDMA

When CSFB SS happened, dial will be triggered.
Then MMI popup should not be shown in case of CDMA CSFB SS.
If the result as CommandsInterface.SS_STATUS_UNKNOWN,
empty string for text which blocks to make popup.
(Refer to createUssdDialog function in PhoneUtils.java)

Bug: 146531989

Change-Id: I7b6a4e498d21b9ffc6ff7c85b80a27b70fc80b2e
Signed-off-by: Jang Hayeong <hayeong.jang@samsung.com>