spi: tegra210-quad: Avoid shift-out-of-bounds

spi: tegra210-quad: Avoid shift-out-of-bounds

A shift-out-of-bounds issue was identified by UBSAN in the
tegra_qspi_fill_tx_fifo_from_client_txbuf() function.

	 UBSAN: shift-out-of-bounds in drivers/spi/spi-tegra210-quad.c:345:27
	 shift exponent 32 is too large for 32-bit type 'u32' (aka 'unsigned int')
	 Call trace:
	  tegra_qspi_start_cpu_based_transfer

The problem arises when shifting the contents of tx_buf left by 8 times
the value of i, which can exceed 4 and result in an exponent larger than
32 bits.

Resolve this by restrict the value of i to be less than 4, preventing
the shift operation from overflowing.

Signed-off-by: Breno Leitao <leitao@debian.org>
Fixes: 921fc1838fb0 ("spi: tegra210-quad: Add support for Tegra210 QSPI controller")
Link: https://patch.msgid.link/20241004125400.1791089-1-leitao@debian.org
Signed-off-by: Mark Brown <broonie@kernel.org>