spi: pl022: update outdated references to pump_transfers()

spi: pl022: update outdated references to pump_transfers()

The pump_transfers tasklet was removed when the driver
switched to the SPI core message processing loop in commit
9b2ef250b31d ("spi: spl022: switch to use default
spi_transfer_one_message()").  The kdoc of
pl022_interrupt_handler() still describes the old flow: scheduling
the pump_transfers tasklet, calling giveback(), and flagging
STATE_ERROR — none of which exist in the current code.  Rewrite
the kdoc to reflect the current paths, which flag errors via
SPI_TRANS_FAIL_IO and call spi_finalize_current_transfer()
directly.

Assisted-by: unnamed:deepseek-v3.2 coccinelle
Signed-off-by: Kexin Sun <kexinsun@smail.nju.edu.cn>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260321105940.8143-1-kexinsun@smail.nju.edu.cn
Signed-off-by: Mark Brown <broonie@kernel.org>