MAINTAINERS: Move Rick Edgecombe to TDX maintainer

MAINTAINERS: Move Rick Edgecombe to TDX maintainer

Per some offline discussion with Kiryl, he could use some help on the TDX
host side. I have worked on the TDX host side for the past few years
including wrangling the initial KVM support, and can help with this.

I am already listed as TDX reviewer. Move it to maintainer.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Link: https://patch.msgid.link/20260527221342.415814-1-rick.p.edgecombe@intel.com