Revert "artik530: bump to ZigBee firmware version to 5.7.4 GA build 99 xNCP 0x6"
Revert "artik530: bump to ZigBee firmware version to 5.7.4 GA build 99 xNCP 0x6"

This reverts commit 5246a0c30a2a40ae3b801cad9eb2cb98a17470c2.

Change-Id: I6eff9b86eeb378c390f53750b0afdb8aac53af6b

SamsungARTIK/build-artik