In the UCF, comment out the following two lines:
# Data path timing depends on the destination clock period
TIMESPEC "TS_axistreamclks_2_axi4liteclks" = FROM axistream_clk TO axi4lite_clk 20000 ps DATAPATHONLY; #assumes axi4lite_clk <= 50 MHz
TIMESPEC "TS_axi4liteclks_2_axistreamclks" = FROM axi4lite_clk TO axistream_clk 6667 ps DATAPATHONLY; #assumes axistream_clk <= 150 MHz