freescale/fs_enet:fix repeated words in comments

Delete the redundant word 'a'.

Signed-off-by: Jilin Yuan <yuanjilin@cdjrlc.com>
Link: https://lore.kernel.org/r/20220629125441.62420-1-yuanjilin@cdjrlc.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>