Washington — President Reagan granted "full and unconditional" pardons to two former top FBI officials, Mark Felt and Edward Miller, who were convicted of approving break-ins during the 1970s hunt for the radical Weathermen. Mr. Felt and Mr. Miller, the FBI's former No. 2 and No. 3 men, were fined a total of $8,500 on the charges, which could have carried a maximum sentence of up to 10 years in jail. The two were indicted in 1978 along with a former acting FBI director, L. Patrick Gra y, on charges they approved the break-ins.