package/nginx: fix patches titles

Changed [PATCH x/y] to [PATCH] at the beginning of the subject line
since the numbering is meaningless.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Martin Bark <martin@barkynet.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>