arm: -march=armv5t for ARM11

In GCC 9 support for the Armv5 and Armv5E architectures (which have no
known implementations) has been removed, cf.
https://gcc.gnu.org/gcc-9/changes.html



Commit 16540d07 ("arm: fix -march for ARM11") changed the value of the
compiler flag from -march=armv5 and -march=armv5t into -march=armv6 for
ARM11.

The values prior to this patch were:

    arch-$(CONFIG_CPU_ARM1136)     =-march=armv5
    arch-$(CONFIG_CPU_ARM1176)     =-march=armv5t

The change lead to a regression with the Raspberry Pi Zero W not booting
anymore.

Use -march=armv5t both for ARM1136 and ARM1176.

Fixes: 16540d07 ("arm: fix -march for ARM11")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Tested-by: Joris Offouga <offougajoris@gmail.com>