MAINTAINERS: remove teikheng

teikheng hasn't reviewed any PRs or engaged in any Zephyr
activity since July 2022.

Recent activities:

- pr: enhance uart ns16550 driver to get clock frequency from clock
  manager
  zephyrproject-rtos#47199
  (2022-07-02T17:31:54Z)
- pr: enhance uart ns16550 driver to get clock frequency from clock
  manager
  zephyrproject-rtos#47167
  (2022-07-01T15:23:39Z)

Signed-off-by: Benjamin Cabé <[email protected]>

Author: kartben

MAINTAINERS.yml

@@ -2858,7 +2858,6 @@ Intel Platforms (Agilex):
     - gdengi
   collaborators:
     - nbalabak
-    - teikheng
   files:
     - boards/intel/socfpga/
     - soc/intel/intel_socfpga/