MAINTAINERS: Remove stale entry for SBL platform driver

Maurice is no longer with Intel and his e-mail address is no longer
active. Remove the stale entry from Slim boot loader section.
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Link: https://lore.kernel.org/r/20231102195218.143440-1-jithu.joseph@intel.comSigned-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

MAINTAINERS

@@ -11025,7 +11025,6 @@ F:	drivers/net/wireless/intel/iwlwifi/
 
 INTEL WMI SLIM BOOTLOADER (SBL) FIRMWARE UPDATE DRIVER
 M:	Jithu Joseph <jithu.joseph@intel.com>
-R:	Maurice Ma <maurice.ma@intel.com>
 S:	Maintained
 W:	https://slimbootloader.github.io/security/firmware-update.html
 F:	drivers/platform/x86/intel/wmi/sbl-fw-update.c