arm, arm64: tweak hard-coded load addresses for PIE binaries

They are used when ASLR is not applied.
The need for adjusting is due to rtld direct exec mode puts ld-elf.so.1
at the PIE load address, and this address must not conflict with the
default linker' load address for non-PIE binaries. Otherwise rtld in
direct mode cannot activate image. Example of implicit failure is ldd(1)
refusing to run.

Reported by: kp
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D37085