hwmon: (pt5161l) Fix bugs in pt5161l_read_block_data()

In the Linux kernel, the following vulnerability has been resolved:

hwmon: (pt5161l) Fix bugs in pt5161l_read_block_data()

Fix two bugs in pt5161l_read_block_data():

1. Buffer overrun: The local buffer rbuf is declared as u8 rbuf[24],
but i2c_smbus_read_block_data() can return up to
I2C_SMBUS_BLOCK_MAX (32) bytes. The i2c-core copies the data into
the caller's buffer before the return value can be checked, so
the post-read length validation does not prevent a stack overrun
if a device returns more than 24 bytes. Resize the buffer to
I2C_SMBUS_BLOCK_MAX.

2. Unexpected positive return on length mismatch: When all three
retries are exhausted because the device returns data with an
unexpected length, i2c_smbus_read_block_data() returns a positive
byte count. The function returns this directly, and callers treat
any non-negative return as success, processing stale or incomplete
buffer contents. Return -EIO when retries are exhausted with a
positive return value, preserving the negative error code on I2C
failure.