edk2: Reformat a bit for readability

- Have only one sed expression per line
- Put the important stuff closer to the command and not hidden in some
continuation line. That is, don't do:

sed \
    <boring stuff> \
    <boring stuff> \
    <boring stuff> \
    <boring stuff> \
    <boring stuff> \
    <IMPORTANT STUFF>

but:

sed <IMPORTANT STUFF> \
    <boring stuff> \
    <boring stuff> \
    <boring stuff> \
    <boring stuff> \
    <boring stuff>