spi: mxic: add missing braces

spi: mxic: add missing braces

Fix the following waring:

drivers/spi/spi-mxic.c: In function ‘mxic_spi_mem_exec_op’:
drivers/spi/spi-mxic.c:401:3: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
   if (op->data.dir == SPI_MEM_DATA_IN)
   ^~
drivers/spi/spi-mxic.c:403:4: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
    if (op->data.dtr)
    ^~

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Zhengxun Li <zhengxunli@mxic.com.tw>
Link: https://lore.kernel.org/r/20210810142405.2221540-1-yangyingliang@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>