Fix a new warning report by build for make ARCH=MIPS allmodconfig:

drivers/spi/spi-cadence-quadspi.c: In function 'cqspi_direct_read_execute':
 ./include/linux/minmax.h:18:28: warning: comparison of distinct pointer types lacks a cast
    18 |  (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
       |                            ^~
 ./include/linux/minmax.h:32:4: note: in expansion of macro '__typecheck'
    32 |   (__typecheck(x, y) && __no_side_effects(x, y))
       |    ^~~~~~~~~~~
 ./include/linux/minmax.h:42:24: note: in expansion of macro '__safe_cmp'
    42 |  __builtin_choose_expr(__safe_cmp(x, y), \
       |                        ^~~~~~~~~~
 ./include/linux/minmax.h:58:19: note: in expansion of macro '__careful_cmp'
    58 | #define max(x, y) __careful_cmp(x, y, >)
       |                   ^~~~~~~~~~~~~
 drivers/spi/spi-cadence-quadspi.c:1153:24: note: in expansion of macro 'max'
  1153 |       msecs_to_jiffies(max(len, 500UL)))) {
       |                        ^~~

"len" is unsigned,however,"500" is unsigned long.
Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/20210107115704.3835282-1-siyanteng@loongson.cnSigned-off-by: Mark Brown <broonie@kernel.org>