spi: tegra210-quad: Refactor error handling into helper functions

spi: tegra210-quad: Refactor error handling into helper functions

Extract common cleanup code into dedicated helper functions to simplify
the code and improve readability. This refactoring includes:

- tegra_qspi_reset(): Device reset and interrupt cleanup
- tegra_qspi_dma_stop(): DMA termination and disable
- tegra_qspi_pio_stop(): PIO mode disable

No functional changes. This is purely a code reorganization to prepare
for improved timeout handling in subsequent patches.

Signed-off-by: Vishwaroop A <va@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://patch.msgid.link/20251028155703.4151791-3-va@nvidia.com
Signed-off-by: Mark Brown <broonie@kernel.org>