qcacld-3.0: Use PLD API to get SOC serial number

Socinfo API is not a standard system API. Hence, use PLD API to get
SOC serial number instead of calling socinfo API directly to enhance
driver portability.

Change-Id: I1d673d2f3b0066f4e05f2f465abc8a6cad7a1f8f
CRs-Fixed: 1069480

core/pld/inc/pld_common.h

@@ -378,4 +378,5 @@ int pld_athdiag_write(struct device *dev, uint32_t offset, uint32_t memtype,
 void *pld_smmu_get_mapping(struct device *dev);
 int pld_smmu_map(struct device *dev, phys_addr_t paddr,
 		 uint32_t *iova_addr, size_t size);
+unsigned int pld_socinfo_get_serial_number(struct device *dev);
 #endif