build: reduce number of files passed to ipk-remove

build: reduce number of files passed to ipk-remove

Instead of using xargs to pass a huge number of files to
script/ipkg-remove, which will usually pick only one, use a more
restrictive wildcard so that, currently, at the most 325 files are
examined, instead of up to over 2,300.  The 325-file package is python,
which is picking up python3* ipks.  It is about to be removed.
Runner-up is ddns-scripts with 7 files.

This makes a second run of make package/luci/compile go from
real 16.40s; user 17.42s; sys 2.73s
to
real 10.71s; user 9.51s; sys 1.27s

There is a caveat though: if one were to remove the ABI_VERSION of a
package that ends in a digit [0-9], then the old package ipk will not be
removed from the bin directory by make package/abc2/clean.

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>