mtd: rawnand: fsl_upm: Fix an off-by one test in fun_exec_op()

In the Linux kernel, the following vulnerability has been resolved: mtd: rawnand: fsl_upm: Fix an off-by one test in fun_exec_op() 'op-cs' is copied in 'fun->mchip_number' which is used to access the 'mchip_offsets' and the 'rnb_gpio' arrays. These arrays have NAND_MAX_CHIPS elements, so the index must be below this limit. Fix the sanity check in order to avoid the NAND_MAX_CHIPS value. This would lead to out-of-bound accesses.