Revert "Merge branch 'mctp-i2c-driver'"

This reverts commit 71812af723, reversing
changes made to cc0be1ad68.

Wolfram Sang says:

Please revert. Besides the driver in net, it modifies the I2C core
code. This has not been acked by the I2C maintainer (in this case me).
So, please don't pull this in via the net tree. The question raised here
(extending SMBus calls to 255 byte) is complicated because we need ABI
backwards compatibility.

Link: https://lore.kernel.org/all/YZJ9H4eM%2FM7OXVN0@shikoro/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/uapi/linux/i2c-dev.h

@@ -39,14 +39,12 @@
 
 
 /* This is the structure as used in the I2C_SMBUS ioctl call */
-#ifndef __KERNEL__
 struct i2c_smbus_ioctl_data {
 	__u8 read_write;
 	__u8 command;
 	__u32 size;
 	union i2c_smbus_data __user *data;
 };
-#endif
 
 /* This is the structure as used in the I2C_RDWR ioctl call */
 struct i2c_rdwr_ioctl_data {

include/uapi/linux/i2c.h

@@ -108,9 +108,6 @@ struct i2c_msg {
 #define I2C_FUNC_SMBUS_READ_I2C_BLOCK	0x04000000 /* I2C-like block xfer  */
 #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK	0x08000000 /* w/ 1-byte reg. addr. */
 #define I2C_FUNC_SMBUS_HOST_NOTIFY	0x10000000 /* SMBus 2.0 or later */
-#define I2C_FUNC_SMBUS_V3_BLOCK		0x20000000 /* Device supports 255 byte block */
-						   /* Note that I2C_SMBUS ioctl only */
-						   /* supports a 32 byte block */
 
 #define I2C_FUNC_SMBUS_BYTE		(I2C_FUNC_SMBUS_READ_BYTE | \
 					 I2C_FUNC_SMBUS_WRITE_BYTE)
@@ -140,15 +137,13 @@ struct i2c_msg {
 /*
  * Data for SMBus Messages
  */
-#define I2C_SMBUS_BLOCK_MAX	32	/* As specified in SMBus 2.0 standard */
-#ifndef __KERNEL__
+#define I2C_SMBUS_BLOCK_MAX	32	/* As specified in SMBus standard */
 union i2c_smbus_data {
 	__u8 byte;
 	__u16 word;
 	__u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
 			       /* and one more for user-space compatibility */
 };
-#endif
 
 /* i2c_smbus_xfer read or write markers */
 #define I2C_SMBUS_READ	1