CONFIG_S5P_EXT_INT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S5P_EXT_INT (not configurable)

modulename: s5p-irq-eint.ko

configname: CONFIG_S5P_EXT_INT

Linux Kernel Configuration
└─>S5P_EXT_INT
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
Use the external interrupts (other than GPIO interrupts.)
Note: Do not choose this for S5P6440 and S5P6450.

source code:
arch/arm/plat-samsung/s5p-irq-eint.c