Revert Return ILLEGAL_ARGUMENT for setting null callback for 2.4 HAL

This reverts part of the CL(ag/24741349) on 2.4 HAL file to pass 2.4
VTS. Since ag/24741349 was just for passing latest VTS on default HAL,
it's ok to keep 2.4 HAL aligned with 2.4's VTS case.

Bug: 320925606
Test: none
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:4e95fdd9a226e3335d4019c0caa61b4f4ced57e3)
Merged-In: I3c5e34930925c466ef6be4209e49122af1c791f6
Change-Id: I3c5e34930925c466ef6be4209e49122af1c791f6