CONFIG_S5P_DEV_USB_EHCI is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S5P_DEV_USB_EHCI (not configurable)

configname: CONFIG_S5P_DEV_USB_EHCI

Linux Kernel Configuration
└─>S5P_DEV_USB_EHCI
In linux kernel since version 3 (release Date: 2011-07-21)  
Compile in platform device definition for USB EHCI