target/i386/cpu: Consolidate the use of warn_report_once()

target/i386/cpu: Consolidate the use of warn_report_once()

The difference between error_printf() and error_report() is the latter
may contain more information, such as the name of the program
("qemu-system-x86_64").

Thus its variant error_report_once() and warn_report()'s variant
warn_report_once() can be used here to print the information only once
without a static local variable "ht_warned".

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Message-ID: <20240327103951.3853425-3-zhao1.liu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>