3.7.3 Configuring the Library
The USB MSD Host Client Driver requires configuration constants to be specified in
                system_config.h file. These constants define the build time
            configuration (functionality and static resources) of the USB MSD Host Client
            Driver.
Macros
| Name | Description | 
| USB_HOST_MSD_INSTANCES_NUMBER | Defines the maximum number of MSD devices to be supported by this host application. | 
| USB_HOST_MSD_LUNS_NUMBER | Defines the maximum number of MSD Device LUNs to be supported in the application. | 
