cmake: kconfig: fix issue if Kconfig symbol name contains lower case
cmake: kconfig: fix issue if Kconfig symbol name contains lower case

Fixes: #40420

If a Kconfig has lower case in its symbol name, then the file configs.c
is wrongly generated.

For example a Kconfig snippet like this:
> config FAIL_this
> 	bool "Test fail"
> 	default y

will create an autoconf.h containing this:
> #define CONFIG_FAIL_this 1

but the configs.c will wrongly contain the same
> #define CONFIG_FAIL_this 1

instead of:
> GEN_ABSOLUTE_SYM_KCONFIG(CONFIG_FAIL_this, 1);

which results in following error at compile time
.../build/zephyr/misc/generated/configs.c: In function '_ConfigAbsSyms':
.../build/zephyr/misc/generated/configs.c:309: warning:
    "CONFIG_FAIL_this" redefined
  309 | #define CONFIG_FAIL_this 1;
      |
In file included from <command-line>:
.../build/zephyr/include/generated/autoconf.h:299: note: this is the
  location of the previous definition
  299 | #define CONFIG_FAIL_this 1
      |

The file misc/generated/CMakeLists.txt has been updated to correctly
handled lower casing in Kconfig symbol names.

Signed-off-by: Torsten Rasmussen <a7c5b1d5a1f41fce6edfa3f7c2392ae0c59deafe@nordicsemi.no>

galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr