Resetting the input descriptor mapping before re-configuring

Removing the mapping was not resetting the input descriptor and display
mapping which caused the original mapping to be still effective. This CL
clears up the variable before reassignment

Bug: 341172990
Bug: 341356351
Flag: TEST_ONLY
Test: atest InputTests
Change-Id: I6927d3a8dc32c204385464f6dee4b8918e7f9cd0