efivar: bump version

efivar: bump version

Drop 0001-Use-z-muldefs-to-avoid-the-multiple-definitions-bug-.patch and
0003-Remove-some-extra-const-that-gcc-complains-about.patch as they are now
upstream.

The upstream repo moved to the 'rhboot' github project, so adjust upstream
URL in .mk and help text to match.

Drop dependency on !musl as it is now support since e04281e60cf0d
(makeguids: Ensure compatibility with other libcs).

Drop BINTARGETS workaround as this is fixed since 6c674283697 (Don't build
static by default).

Drop popt dependency as it is no longer needed since 1aec5e7891 (Replace
popt usage with getopt_long in efivar.c).

While we are at it, also add a hash for the license file.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>