spi: hisi-kunpeng: Fix Woverflow warning on conversion

Fix warning Woverflow on type conversion reported on x86_64:

  drivers/spi/spi-hisi-kunpeng.c:361:9: warning: conversion from 'long unsigned int' to 'u32'
  {aka 'unsigned int'} changes value from '18446744073709551600' to '4294967280' [-Woverflow]

The registers are 32 bit, so fix by casting to u32.

Fixes: c770d863 ("spi: Add HiSilicon SPI Controller Driver for Kunpeng SoCs")
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jay Fang <f.fangjian@huawei.com>
Link: https://lore.kernel.org/r/1617762660-54681-1-git-send-email-f.fangjian@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-hisi-kunpeng.c

@@ -358,7 +358,7 @@ static int hisi_spi_transfer_one(struct spi_controller *master,
 	smp_mb();
 
 	/* Enable all interrupts and the controller */
-	writel(~IMR_MASK, hs->regs + HISI_SPI_IMR);
+	writel(~(u32)IMR_MASK, hs->regs + HISI_SPI_IMR);
 	writel(1, hs->regs + HISI_SPI_ENR);
 
 	return 1;