sonic-buildimage: Remove disable-pcie-firmware-check brcm config on PikeZ (sonic-net#20619)

Remove the check as the platform is strapped to load the pcie firmware
and we should be able to keep the SDK check to ack the firmware was
loaded instead of skipping the verification.

Signed-off-by: Aaron Payment <aaronp@arista.com>

Author: aaronpayment

device/arista/x86_64-arista_720dt_48s/td3x2-a720dt-48s-flex.config.bcm

@@ -5,7 +5,6 @@ bcm_num_cos.0=9
 bcm_stat_flags=1
 bcm_stat_jumbo.0=9236
 cdma_timeout_usec.0=15000000
-disable_pcie_firmware_check.0=1
 dma_desc_timeout_usec.0=15000000
 fpem_mem_entries.0=0
 higig2_hdr_mode.0=1