Refine pattern for Depthcharge TFTP error messages
Refine pattern used to match Depthcharge TFTP errors. This prevents LAVA from wrongly matching similar errors in Coreboot's late phase output.
MR upstream: https://git.lavasoftware.org/lava/lava/-/merge_requests/1783
Signed-off-by: Laura Nao laura.nao@collabora.com