ARM: zImage: remove the static qualifier from global data variables

To be able to relocate the .bss section at run time independently from
the rest of the code, we must make sure that no GOTOFF relocations are
used with .bss symbols.  This usually means that no global variables can
be marked static unless they're also const.

Let's remove the static qualifier from current offenders, or turn them
into const variables when possible.  Next commit will ensure the build
fails if one of those is reintroduced due to otherwise enforced coding
standards for the kernel.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Tony Lindgren <tony@atomide.com>