NFC: trf7970a: Remove unnecessary FIFO reset & RSSI read

It is no longer necessary to reset the FIFO and
read the 'RSSI Levels and Oscillator Status Register'
so remove that code.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>