xen: x86: remove setting the obsolete config XEN_MAX_DOMAIN_MEMORY

Commit c70727a5 ("xen: allow more than 512 GB of RAM for 64 bit
pv-domains") from July 2015 replaces the config XEN_MAX_DOMAIN_MEMORY with
a new config XEN_512GB, but misses to adjust arch/x86/configs/xen.config.
As XEN_512GB defaults to yes, there is no need to explicitly set any config
in xen.config.

Just remove setting the obsolete config XEN_MAX_DOMAIN_MEMORY.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220817044333.22310-1-lukas.bulwahn@gmail.comSigned-off-by: Juergen Gross <jgross@suse.com>

arch/x86/configs/xen.config

@@ -14,7 +14,6 @@ CONFIG_CPU_FREQ=y
 
 # x86 xen specific config options
 CONFIG_XEN_PVH=y
-CONFIG_XEN_MAX_DOMAIN_MEMORY=500
 CONFIG_XEN_SAVE_RESTORE=y
 # CONFIG_XEN_DEBUG_FS is not set
 CONFIG_XEN_MCE_LOG=y