ASRock E350M1: irq_tables.c: Include `cpu/amd/amdfam14.h` for `get_bus_conf`

ASRock E350M1: irq_tables.c: Include `cpu/amd/amdfam14.h` for `get_bus_conf`

When building the ASRock E350M1, the following warning is shown.

    $ make # on Jenkins (build server)
    […]
        CC         mainboard/asrock/e350m1/irq_tables.ramstage.o
    src/mainboard/asrock/e350m1/irq_tables.c: In function 'write_pirq_routing_table':
    src/mainboard/asrock/e350m1/irq_tables.c:64:2: warning: implicit declaration of function 'get_bus_conf' [-Wimplicit-function-declaration]
    […]

Including the header file `cpu/amd/amdfam14.h` declaring the
function addresses this warning.

The same change was done in the following commit for the
AMD Persimmon board.

    commit d7a696d0f229abccc95ff411f28d91b9b796ab74
    Author: efdesign98 <efdesign98@gmail.com>
    Date:   Thu Sep 15 15:24:26 2011 -0600

        Persimmon updates for AMD F14 rev C0

        Reviewed-on: http://review.coreboot.org/137

Change-Id: I40b5735feb7116961ca0c4d6940ec55cdf42d3c6
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/2956
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martin.roth@se-eng.com>