brcm63xx-arm: remove non-supported boards

iopsys-brcm63xx-arm/Config.in

...brcm63xx-arm/base-files/etc/board-db/boards/963158REF_ARC

iopsys-brcm63xx-arm/base-files/etc/board-db/boards/EG400R0

iopsys-brcm63xx-arm/base-files/etc/board-db/boards/F104W

iopsys-brcm63xx-arm/base-files/etc/board-db/boards/XCE572

iopsys-brcm63xx-arm/base-files/etc/board-db/boards/XCE573

iopsys-brcm63xx-arm/config/arc63158ref/config

iopsys-brcm63xx-arm/config/eg400/config

iopsys-brcm63xx-arm/config/f104w/config

iopsys-brcm63xx-arm/config/srcmm6752ref/config

iopsys-brcm63xx-arm/image/Config.in

iopsys-brcm63xx-arm/profiles/iopsys.mk