sk: handle erorors of lseek
sk: handle erorors of lseek

CID 159475 (#1 of 1): Unchecked return value from library (CHECKED_RETURN)
1. check_return: Calling lseek(img_raw_fd(img), pkt->entry->length, 1)
   without checking return value. This library function may fail and return an error code.

Signed-off-by: Andrew Vagin <74c05afa918858348d6db8037d82fa8124870113@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@virtuozzo.com>

KKoukiou/criu-remote,efiop/criu,eabatalov/criu,KKoukiou/criu-remote,KKoukiou/criu-remote,eabatalov/criu,efiop/criu,efiop/criu,efiop/criu,efiop/criu,efiop/criu,KKoukiou/criu-remote,eabatalov/criu,eabatalov/criu,eabatalov/criu,KKoukiou/criu-remote,KKoukiou/criu-remote,eabatalov/criu