| Compiling with GCC-12 leads to an error:
    +board/xilinx/common/board.c:479:37: error: the comparison will always
     evaluate as 'true' for the address of 'mac_addr' will never be NULL
     [-Werror=address]
    +  479 |                                 if (!desc->mac_addr[i])
    +      |                                     ^
Remove the redundant check.
Fixes:  | ||
|---|---|---|
| .. | ||
| Makefile | ||
| board.c | ||
| board.h | ||
| cpu-info.c | ||
| fru.c | ||
| fru.h | ||
| fru_ops.c | ||