ppe_inject.c: fix output injection files to have the correct frequency factor in their file names
This patch fixes a minor bug in the ppe_inject.c code that is part of lalapps_pulsar_parameter_estimation_nested. If the code was being used to generate fake data, and it was requested that the code output that fake data, then it would be output to a file name with the suffix giving by the frequency harmonic (e.g., 2.0 for twice the rotation frequency, or 1.0 for the rotation frequency) of the data produced. If producing fake data at both 1 and 2f, the code was appending the wrong suffix to the output file name, i.e. 1.0 for the data stream containing 2f data and vice versa. This has been fixed. Internally the data was still used in its correct context, so this was just an issue for the output file names. These fake data output files have never been used for any real analysis, so there is no problem with any previous studies.