dwc3: gadget: Use default TX FIFO size as 1024 bytes with each IN eps

Commit d8a39efa ("dwc3: gadget: Improve TX FIFO resize functionality")
is considering USB enumerated speed to allocate TX FIFO size for each IN
endpoints. This change simplifies this by using 1024 bytes as default
TXFIFO size with each IN endpoints.

Change-Id: I55b5886c824d9b689ac8496f50f6e0e784afae98
Signed-off-by: Mayank Rana <mrana@codeaurora.org>