qemu/bswap: Remove unused qemu_bswap_len()

Last use of qemu_bswap_len() has been removed in commit
e5fd1eb0 ("apb: add busA qdev property to PBM PCI bridge").

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200928131934.739451-2-philmd@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

include/qemu/bswap.h

@@ -169,12 +169,6 @@ CPU_CONVERT(le, 16, uint16_t)
 CPU_CONVERT(le, 32, uint32_t)
 CPU_CONVERT(le, 64, uint64_t)
 
-/* len must be one of 1, 2, 4 */
-static inline uint32_t qemu_bswap_len(uint32_t value, int len)
-{
-    return bswap32(value) >> (32 - 8 * len);
-}
-
 /*
  * Same as cpu_to_le{16,32}, except that gcc will figure the result is
  * a compile-time constant if you pass in a constant.  So this can be