samples: net: zperf: Add correct .conf file name for mimxrt1060_evk

Change the name of the mimxrt1060_evk conf file (mimxrt1060_evk.conf) to
the correct name, "mimxrt1060_evk_mimxrt1062_qspi.conf". This change
causes net related code to be placed into ITCM on mimxrt1060_evk boards

Signed-off-by: Jacob Wienecke <jacob.wienecke@nxp.com>