This reverts commit a844adfd.
The commit a844adfd is degrading rx sensitivity of lower rate in
HT40 mode and it is confirmed that reverting the change is
improving rx sensitivity.

spur_freq_sd (for self-corr in AGC) is defined with respect to the
center of each 20MHz channel while spur_phase_delta (for self-corr
in Rx and spur data filter) is defined with respect to the center
of current RF channel.

So in short, we need to subtract spur_freq_sd (for self-corr in AGC)
by the offset between the center of primary20 and the center of RF
channel in SW. This offset could be +/10 MHz for dynamic 40.

Cc: Madhan Jaganathan <madhanj@qca.qualcomm.com>
Signed-off-by: Kai Shi <kaishi@qca.qualcomm.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>