bugfix: seek FM stations

[andreyvorobyov2]

Hi.
FM station search works fine, but
after a successful station search, the frequency changes using the method

g_si4735.setFrequency(g_currentFrequency);

and the found station is lost.
After deleting this line, the found frequency doesn't change.

Fixed in the second commit
When RDS is enabled, the station search doesn't start because condition

else if (g_displayRDS)

is earlier than

else if (g_currentMode == FM || g_currentMode == AM)
  doSeek();