CONFIG_S5P_GPIO_DRVSTR is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S5P_GPIO_DRVSTR (not configurable)

configname: CONFIG_S5P_GPIO_DRVSTR

Linux Kernel Configuration
└─>Samsung Common options
└─>S5P_GPIO_DRVSTR
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
Internal configuration to get and set correct GPIO driver strength
helper