rustfmt: use entrypoint full path

This PR swaps any calls to the `entrypoint!` macro with the full path, ie: `solana_program::entrypoint!`.

This will play a role in the effort to introduce a linting standard to SPL.

program/src/entrypoint.rs

@@ -2,11 +2,11 @@
 
 use crate::{error::TokenError, processor::Processor};
 use solana_program::{
-    account_info::AccountInfo, entrypoint, entrypoint::ProgramResult,
-    program_error::PrintProgramError, pubkey::Pubkey,
+    account_info::AccountInfo, entrypoint::ProgramResult, program_error::PrintProgramError,
+    pubkey::Pubkey,
 };
 
-entrypoint!(process_instruction);
+solana_program::entrypoint!(process_instruction);
 fn process_instruction(
     program_id: &Pubkey,
     accounts: &[AccountInfo],