CONFIG_DS1603 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
default or selected kernelversion does not have config value CONFIG_DS1603.
Result is shown for kernelversion 6.9.9

DS1603 RTC driver

modulename: ds1603.ko

configname: CONFIG_DS1603

Linux Kernel Configuration
└─>DS1603 RTC driver
In linux kernel since version 2.6.12  
source code:
arch/mips/lasat/ds1603.c
depends
CONFIG_LASAT