Revert "usb: gadget: mtp: Increase RX transfer length to 1M"

This reverts commit 0db49c2550a09458db188fb7312c66783c5af104.

This results in kmalloc() abuse to find a large number of contiguous
pages, which thrashes the page allocator and hurts overall performance.
I couldn't reproduce the improved MTP throughput that this commit
claimed either, so just revert it.

Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: Ruchit <ruchitmarathe@gmail.com>

drivers/usb/gadget/function/f_mtp.c

@@ -55,7 +55,6 @@
 	ipc_log_string(_mtp_ipc_log, "%s: " fmt,  __func__, ##__VA_ARGS__)
 #endif
 
-#define MTP_RX_BUFFER_INIT_SIZE    1048576
 #define MTP_BULK_BUFFER_SIZE       16384
 #define INTR_BUFFER_SIZE           28
 #define MAX_INST_NAME_LEN          40
@@ -92,7 +91,7 @@
 
 #define MAX_ITERATION		100
 
-unsigned int mtp_rx_req_len = MTP_RX_BUFFER_INIT_SIZE;
+unsigned int mtp_rx_req_len = MTP_BULK_BUFFER_SIZE;
 module_param(mtp_rx_req_len, uint, 0644);
 
 unsigned int mtp_tx_req_len = MTP_BULK_BUFFER_SIZE;