common/sfc_efx/base: fix dereferencing null pointer
common/sfc_efx/base: fix dereferencing null pointer

In function efx_pci_xilinx_cap_tbl_find, pointer entry_offsetp is used
before null pointer check, which may cause access to null pointer.

This patch fix this problem.

Fixes: ba9568b8b4b7 ("common/sfc_efx/base: add Xilinx capabilities table lookup")
Cc: stable@dpdk.org

Signed-off-by: Hongbo Zheng <ac635125c10ac53d300b049dad8f4b0c8fe7406c@huawei.com>
Signed-off-by: Min Hu (Connor) <f02e10cb0a484c51b0f8634f83fbb4ab9ded1c6a@huawei.com>
Reviewed-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk