arm/paravirt: Use common code for paravirt_steal_clock()

Remove the arch-specific variant of paravirt_steal_clock() and use
the common one instead.

This allows to remove paravirt.c and paravirt.h from arch/arm.

Until all archs supporting Xen have been switched to the common code
of paravirt_steal_clock(), drivers/xen/time.c needs to include
asm/paravirt.h for those archs, while this is not necessary for arm
any longer.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260105110520.21356-8-jgross@suse.com

Author: jgross1

arch/arm/Kconfig

@@ -1320,6 +1320,7 @@ config UACCESS_WITH_MEMCPY
 
 config PARAVIRT
 	bool "Enable paravirtualization code"
+	select HAVE_PV_STEAL_CLOCK_GEN
 	help
 	  This changes the kernel so it can modify itself when it is run
 	  under a hypervisor, potentially improving performance significantly

arch/arm/include/asm/paravirt.h

@@ -83,7 +83,6 @@ AFLAGS_iwmmxt.o			:= -Wa,-mcpu=iwmmxt
 obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o
 obj-$(CONFIG_VDSO)		+= vdso.o
 obj-$(CONFIG_EFI)		+= efi.o
-obj-$(CONFIG_PARAVIRT)	+= paravirt.o
 
 obj-y			+= head$(MMUEXT).o
 obj-$(CONFIG_DEBUG_LL)	+= debug.o

arch/arm/kernel/Makefile

@@ -10,7 +10,9 @@
 #include <linux/static_call.h>
 #include <linux/sched/cputime.h>
 
+#ifndef CONFIG_HAVE_PV_STEAL_CLOCK_GEN
 #include <asm/paravirt.h>
+#endif
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>