Darshan HDF5 module warnings when not using MPI-IO VFL

Using Darshan's HDF5 module with applications that are using a VFL other than MPI-IO result in output like the following:

HDF5-DIAG: Error detected in HDF5 (1.12.0) MPI-process 5:
  #000: ../../src/H5FDmpio.c line 376 in H5Pget_fapl_mpio(): VFL driver is not MPI-I/O
    major: Property lists
    minor: Bad value`

Darshan is using the H5Pget_fapl_mpio() function to determine whether the user is using MPI-IO VFL, but it looks like that will result in warning messages if the user is using something different. Looks like we should modify to use H5Pget_driver() instead.