Arm tests: reduce objdump's output and improve some matching patterns

Arm tests: reduce objdump's output and improve some matching patterns

Linker scripts can change the sections order in the output. Some matching
patterns in tests try to detect the end of a section by detecting the
beginning of the next one. However, they mistakenly enforce the name of
the next section without any need. This caused the tests to break due to
minor changes to the linker scripts.

This patch adds '-j <interesting-section>' to the arguments of objdump
to dump only relevant information for the tests. This removed the issue
related to the ordering of the sections. The matching patterns were also
made stricter to match better the expected output.