This reverts commit 33ec8cb,
so that barebox can once again match against "arm,armv7-timer"
compatibles. The reverted commit restricted the timer to CPU_V8,
because in i.MX multi-image configuration with MACH_SCB9328 set,
we can have both CPU_32v7 and CPU_32v4T in the same build.

To avoid this issue properly, force use of -march=armv7-a for
non-CONFIG_CPU_V8 targets. This is acceptable as we don't expect
non-ARMv7 device trees to have the architected arm,armv7-timer.

Suggested-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>