arch/arm/src/armv6-m/CMakeLists.txt: fix undefined reference to `up_show_cpuinfo'

Aligned Cmakefile with Make.defs PR #10132

fix

FAILED: nuttx
C:\WINDOWS\system32\cmd.exe /C "cd . && D:\nx20250410\tools\gcc-arm-none-eabi\bin\arm-none-eabi-gcc.exe  --specs=nosys.specs   -Wl,--print-memory-usage -Wl,--entry=__start -nostdlib -Wl,--gc-sections -Wl,--cref -Wl,-Map=nuttx.map @CMakeFiles\nuttx.rsp -o nuttx && cd ."
D:/nx20250410/tools/gcc-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/13.2.1/../../../../arm-none-eabi/bin/ld.exe: fs/libfs.a(fs_procfscpuinfo.c.obj): in function `cpuinfo_read':
D:/rp2040/nuttx/fs/procfs/fs_procfscpuinfo.c:160:(.text.cpuinfo_read+0xa): undefined reference to `up_show_cpuinfo'

Signed-off-by: simbit18 <[email protected]>

Author: simbit18

Diff for: arch/arm/src/armv6-m/CMakeLists.txt

@@ -23,6 +23,7 @@
 set(SRCS
     arm_exception.S
     arm_saveusercontext.S
+    arm_cpuinfo.c
     arm_doirq.c
     arm_hardfault.c
     arm_initialstate.c