BSP settings moved from bsp.h to syscfg.yml

[Christopher Collins]

Hello all,

Just a heads up- I will be merging a pull request which moves some BSP
settings from `bsp.h` to `syscfg.yml`
(https://github.com/apache/mynewt-core/pull/499).  If your BSP
uses non-default values for these settings, you'll need to add overrides
to your BSP's `syscfg.yml` file.

The new settings are below:

    NFFS_NUM_AREAS:
        description: >
            Number of areas to allocate in the NFFS disk.  A smaller number is
            used if the flash hardware cannot support this value.
        value: 8

    CONFIG_FCB_NUM_AREAS:
        description: >
            Number of areas to allocate in the config FCB.  A smaller number is
            used if the flash hardware cannot support this value.
        value: 8

    BOOT_SERIAL_DETECT_PIN:
        description: >
            Start the serial boot loader if this pin is asserted at boot time.
        value:
        restrictions:
            - '$notnull'

    BOOT_SERIAL_DETECT_PIN_CFG:
        description: >
            GPIO configuration for the serial boot loader detect pin.
        value: 'HAL_GPIO_PULL_UP'

    BOOT_SERIAL_DETECT_PIN_VAL:
        description: >
            The value the detect pin must be set to for the serial boot loader
            to start.
        value: 0

    BOOT_SERIAL_REPORT_PIN:
        description: >
            The GPIO to toggle while the serial boot loader is running.  Set to
            -1 to disable reporting.
        value: 'LED_BLINK_PIN'

    BOOT_SERIAL_REPORT_FREQ:
        description: >
            The toggle rate, in Hz, of the serial boot loader report pin.
        value: 4

Thanks,
Chris