x86/hyperv: Set pv_info.name to "Hyper-V"

Michael reported that the x86/hyperv initialization code prints the
following dmesg when running in a VM on Hyper-V:

[ 0.000738] Booting paravirtualized kernel on bare hardware

Let the x86/hyperv initialization code set pv_info.name to "Hyper-V" so
dmesg reports correctly:

[ 0.000172] Booting paravirtualized kernel on Hyper-V

[ tglx: Folded build fix provided by Yue ]

Reported-by: Michael Kelley <[e-mail]>
Signed-off-by: Andrea Parri <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Reviewed-by: Wei Liu <[e-mail]>
Reviewed-by: Michael Kelley <[e-mail]>
Cc: YueHaibing <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]

arch/x86/kernel/cpu/mshyperv.c

···
 	int hv_host_info_ecx;
 	int hv_host_info_edx;
 
+#ifdef CONFIG_PARAVIRT
+	pv_info.name = "Hyper-V";
+#endif
+
 	/*
 	 * Extract the features and hints
 	 */