ide: remove duplicated assignment to 'cursg'

Pointer cursg is initialized to cmd->cursg and again re-assigned the
same value a few lines later, hence the second assignment is redundant
and can be removed.

Cleans up clang warning:
drivers/ide/ide-taskfile.c:229:22: warning: Value stored to 'cursg'
during its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>