x86/paravirt: Switch time pvops functions to use static_call()

The time pvops functions are the only ones left which might be
used in 32-bit mode and which return a 64-bit value.

Switch them to use the static_call() mechanism instead of pvops, as
this allows quite some simplification of the pvops implementation.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-5-jgross@suse.com
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2792879..107acc4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -777,6 +777,7 @@
 
 config PARAVIRT
 	bool "Enable paravirtualization code"
+	depends on HAVE_STATIC_CALL
 	help
 	  This changes the kernel so it can modify itself when it is run
 	  under a hypervisor, potentially improving performance significantly