mk-pxelinux-ramfs: case insensitive arg parsing
mk-pxelinux-ramfs: case insensitive arg parsing

Many documentations refer to kernel, initrd, ... arguments
in upper case so the grep/sed should support both.

GitHub-ID: #16

Signed-off-by: Christian Ehrhardt <48da28e2c2cd455d60e19b14c46925e20a3c5d5b@canonical.com>
Acked-by: Viktor Mihajlovski <a96a137ca8976b5ff3114c85be7aeb3b6464dad7@linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <db4757c56f54651f568cc7cda79cd93c781b1605@linux.vnet.ibm.com>

ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools