dump: Replace TARGET_PAGE_SIZE -> qemu_target_page_size()

TARGET_PAGE_SIZE is target specific. In preparation of
making dump.c target-agnostic, replace the compile-time
TARGET_PAGE_SIZE definition by runtime qemu_target_page_size().

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20230225094903.53167-3-philmd@linaro.org>