xen/arm32: avoid .rodata to be marked as executable

xen/arm32: avoid .rodata to be marked as executable

The section .proc.info lives in .rodata as it doesn't contain any
executable code. However, the section is still marked as executable
as the consequence .rodata will also be marked executable.

Xen doesn't use the ELF permissions to decide the page-table mapping
permission. However, this will confuse disassemblers.

'#execinstr' is now removed on all the pushsection dealing with
.proc.info

Signed-off-by: Jan Beulich <jbeulich@suse.com>
[julieng: Rework the commit message]
Acked-by: Julien Grall <jgrall@amazon.com>