Some i.MX SoCs (e.g. i.MX7) have FEC registers going as far as offset
0x614, so to avoid getting aborts when accessing those on QEMU, extend
the register file to cover FSL_IMX25_FEC_SIZE(16K) of address space
instead of just 1K.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
Cc: qemu-devel@nongnu.org
Cc: qemu-arm@nongnu.org
Cc: yurovsky@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>