samples: pktgen: correct dev to DEV

samples: pktgen: correct dev to DEV

[ Upstream commit 3342dc8b4623d835e7dd76a15cec2e5a94fe2f93 ]

In the pktgen_sample01_simple.sh script, the device variable is uppercase
'DEV' instead of lowercase 'dev'. Because of this typo, the script cannot
enable UDP tx checksum.

Fixes: 460a9aa23de6 ("samples: pktgen: add UDP tx checksum support")
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://patch.msgid.link/20241112030347.1849335-1-wei.fang@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>