hw/arm/raspi: Remove ignore_memory_transaction_failures on the raspi2

hw/arm/raspi: Remove ignore_memory_transaction_failures on the raspi2

Commit 1c3db49d39 added the raspi3, which uses the same peripherals
than the raspi2 (but with different ARM cores). The raspi3 was
introduced without the ignore_memory_transaction_failures flag.
Almost 2 years later, the machine is usable running U-Boot and
Linux.
In commit 00cbd5bd74 we mapped a lot of unimplemented devices,
commit d442d95f added thermal block and commit 0e5bbd7406 the
system timer.
As we are happy with the raspi3, let's remove this flag on the
raspi2.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Luc Michel <luc.michel@greensocs.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20200921034729.432931-4-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>