nvmet: replace kmalloc + memset with kzalloc for data allocation

nvmet: replace kmalloc + memset with kzalloc for data allocation

cocci warnings: (new ones prefixed by >>)
>> drivers/nvme/target/pr.c:831:8-15: WARNING: kzalloc should be used for data, instead of kmalloc/memset

The pattern of using 'kmalloc' followed by 'memset' is replaced with
'kzalloc', which is functionally equivalent to 'kmalloc' + 'memset',
but more efficient. 'kzalloc' automatically zeroes the allocated
memory, making it a faster and more streamlined solution.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202411301434.LEckbcWx-lkp@intel.com/
Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Yu-Chun Lin <eleanor15x@gmail.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>