smem: msm: add missing <linux/sizes.h>

MSM SMEM driver is currently missing <linux/sizes.h> header and throws
the following compile error:

drivers/smem/msm_smem.c: In function ‘qcom_smem_get_ptable’:
drivers/smem/msm_smem.c:635:71: error: ‘SZ_4K’ undeclared (first use in this function)
  635 |         ptable = smem->regions[0].virt_base + smem->regions[0].size - SZ_4K;

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Cc: luka.perkov@sartura.hr