Code review feedback - LendingPool contract

[redlarva]

• Validate reserve data is not empty:
  In our current implementation, some of the methods such as redeem, borrow, repay, deposit, and liquidationCall do not validate whether the reserve data is empty before proceeding with the function. This can lead to potential errors, such as null pointer exceptions. To avoid these issues, we will add a validation check to ensure that the reserve data is not empty before proceeding with any of these methods.

• Use caller address as reserve for liquidation:
  In our liquidationCall method, we are currently using a params value to determine the address of the reserve which we can avoid and use caller address to identify reserve.