ANDROID: KVM: arm64: wait_for_initramfs for pKVM module loading procfs

Of course, the initramfs needs to be ready before procfs can be
mounted... in the initramfs. While at it, only mount if a pKVM module
must be loaded and only print a warning in case of failure.

Bug: 278749606
Bug: 301483379
Bug: 331152809
Change-Id: Ie56bd26d4575f69cb1f06ba6317a098649f6da44
Reported-by: Mankyum Kim <mankyum.kim@samsung-slsi.corp-partner.google.com>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
(cherry picked from commit 7d5843b5)