qcacld-3.0: Remove csrValidateCountryString() prototype

Function csrValidateCountryString() no longer exists, but there is
still an obsolete prototype for it, so remove it.

Change-Id: I40869b7160cbc3e64b785e44711237455f2e02b0
CRs-Fixed: 2255482

core/sme/inc/csr_support.h

@@ -317,7 +317,6 @@ QDF_STATUS csr_parse_bss_description_ies(tHalHandle hHal,
 QDF_STATUS csr_get_parsed_bss_description_ies(tHalHandle hHal,
 		tSirBssDescription *pBssDesc, tDot11fBeaconIEs **ppIEStruct);
 
-bool csrValidateCountryString(tHalHandle hHal, uint8_t *pCountryString);
 tSirScanType csr_get_scan_type(tpAniSirGlobal pMac, uint8_t chnId);
 uint8_t csr_to_upper(uint8_t ch);
 QDF_STATUS csr_get_phy_mode_from_bss(tpAniSirGlobal pMac,