Documentation: embargoed-hardware-issues.rst: Add myself for Power

Adding myself as the contact for Power

Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://lore.kernel.org/r/20250614152925.82831-1-maddy@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: maddy-kerneldev

Documentation/process/embargoed-hardware-issues.rst

@@ -290,6 +290,7 @@ an involved disclosed party. The current ambassadors list:
   AMD		Tom Lendacky <thomas.lendacky@amd.com>
   Ampere	Darren Hart <darren@os.amperecomputing.com>
   ARM		Catalin Marinas <catalin.marinas@arm.com>
+  IBM Power	Madhavan Srinivasan <maddy@linux.ibm.com>
   IBM Z		Christian Borntraeger <borntraeger@de.ibm.com>
   Intel		Tony Luck <tony.luck@intel.com>
   Qualcomm	Trilok Soni <quic_tsoni@quicinc.com>