[aarch64] Remove handling of ADR/ADRP from prologue analyzer

[aarch64] Remove handling of ADR/ADRP from prologue analyzer

As reported by Tom in https://sourceware.org/pipermail/gdb-patches/2022-August/191357.html,
the aarch64 prologue analyzer considers the adrp instruction in the
gdb.dwarf2/dw2-dir-file-name.exp testcase to be part of a prologue.

The function has no prologue though, and it only loads the volatile variable
from memory.  GDB should not skip any instructions in this case.

Doing some archaeology, it seems handling for adr/adrp in prologues was
included with the original aarch64 port.  It might've been an oversight.

In the particular case of gdb.dwarf2/dw2-dir-file-name.exp, the analyzer skips
a couple instructions and leaves us in a nice spot where the address to the
variable "v" is already in w0. But no prologues exists.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29481