staging: r8188eu: refactor field of struct odm_rf_cal

staging: r8188eu: refactor field of struct odm_rf_cal

Refactor the field IQKMatrixRegSetting of struct odm_rf_cal to be not
an array. The driver is for chips that operate in the 2.4 GHz band only.
So only the first element of the array is used and there is no need for
an array.

Acked-by: Phillip Potter <phil@philpotter.co.uk>
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20210829175624.5915-2-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>