OvmfPkg/EnrollDefaultKeys: clean up global variable name prefixes

OvmfPkg/EnrollDefaultKeys: clean up global variable name prefixes

In edk2, we should start the names of module-global variables with "m".
Rename the "RedHatPkKek1", "MicrosoftKEK", "MicrosoftPCA",
"MicrosoftUefiCA" variables accordingly, with the following command:

  sed --regexp-extended --in-place \
    --expression='s,\<(RedHatPkKek1|Microsoft(KEK|PCA|UefiCA))\>,m\1,g' \
    OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien.grall@arm.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1747
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Gary Lin <glin@suse.com>