TI CC2545 supports how many Channels for 1Mbps and 2Mbps Data Rate
It says right there in the data sheet text that you copied:


  "...the carrier frequency is set by using the register PRF_CHAN.FREQ.
  The carrier frequency is 2379 + n MHz, where n is the value of this
  register, where n can be from 0 to 116. This gives a frequency range
  from 2379 MHz to 2495 MHz."


So there you have it. There are 117 channels possible. Obviously you have to check if all those channel frequencies are legal for the band in your area and at what power level.

You also have to take into account the data modulation rate. Clearly if you are using a data rate up to 2Mbps you will likely be limited to half or less number of channels. If half you would have to confine usage to carriers of the odd frequency numbers or even frequency numbers.