dump: Consolidate phdr note writes

There's no need to have two write functions. Let's rather have two
functions that set the data for elf 32/64 and then write it in a
common function.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220330123603.107120-8-frankja@linux.ibm.com>