mini-iconv: Don't use ${PN}
Don't use ${PN} for the source dir, it will break multilib builds.
The correct variable is ${BPN}.
Cc: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Khem Raj <raj.khem@gmail.com>