x86: drop "depends on X86" for TBOOT Kconfig option

Given that this file already resides under arch/x86, there is no need
to have the dependency.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/Kconfig

@@ -130,7 +130,6 @@ config HVM_FEP
 config TBOOT
 	def_bool y
 	prompt "Xen tboot support" if EXPERT = "y"
-	depends on X86
 	select CRYPTO
 	---help---
 	  Allows support for Trusted Boot using the Intel(R) Trusted Execution