wifi: Use hidl_return_util functions in WifiChip

Modify the WifiChip methods to the use the new helper functions.

Also,
1. Modify the WifiLegacyHal.requestDriverMemoryDump &
WifiLegacyHal.requestDriverMemoryDump to return a vector of |uint8_t|
instead of |char| to avoid unnecessary typecasting in the HIDL methods.
2. Remove |createHidlVecOfIfaceNames| helper function as most of the
necessary conversion should be handled by hidl_vec/hidl_string
constructors.

Bug: 32337072
Test: Compiles

Change-Id: Ic0b7aa2a5a078e53d5bc5bef18995a3cc0f548a1