pipe 1 does not need dynamic payloads enabled to transmit ACK payloads

[2bndy5]

The following line of code from enableAckPayload() is a bit erroneous.

write_register(DYNPD, read_register(DYNPD) | _BV(DPL_P1) | _BV(DPL_P0))

should be changed to

write_register(DYNPD, read_register(DYNPD) | _BV(DPL_P0))

Because enabling the dynamic payloads feature on pipe 1 is not needed to transmit ACK payloads, the configuration of pipe 1 should be left up to the user in this context. Of course, the examples should demonstrate proper pipe usage rather than letting the library hide (& probably confuse people about) the requirement to enable the dynamic payloads feature for pipes using ACK payloads in RX mode.

Examples/tests affected:

1. GettingStarted_CallResponse.ino (from "examples/GettingStarted_CallResponse" folder)
2. pingpair_ack.ino (from "examples/pingpair_ack" folder)
3. pingpair_irq.ino (from "examples/pingpair_irq" folder)
4. gettingstarted_call_response.cpp (from "examples_linux" folder)
5. gettingstarted_call_response_int.cpp (from "examples_linux/interrupts" folder)
6. gettingstarted_call_response_int2.cpp (from "examples_linux/interrupts" folder)
7. pingpair_test.pde (from "tests/native" folder)
8. pingpair_irq.pde (from "tests/pingpair_test" folder)

The note about this line of code in the docs should also be amended accordingly.

[2bndy5]

a bit erroneous.

I inadvertently made a pun! 😄